HOW TO CHEAT ON YOUR GIRLFRIEND! is a Smosh video uploaded on May 25, 2012. It is the fifth installment in the "How-To" series. These are some very helpful tips to help you cheat on your girlfriend.
Assuming the viewer is male, Anthony says, "Hi. Have you ever met the girl of your dreams and would do anything in the world to be with her, except break up with your current girlfriend cause you're a giant douchebag? Well I know I have, so I'm going to show you how to cheat! Let's go!"
Anthony's girlfriend asks, "What's that, babe?" Anthony answers, "Nothing honey. YEEHAW!" and rides his girlfriend off screen.
Wear a Disguise
A blonde woman is sitting at a table laughing at Anthony's joke, while he is hiding behind a bush. His original girlfriend walks up to her and asks, "Jenna? What are you doing here?" The blonde answers, "Oh nothing. I'm just hanging out with Anthon-a bush.His real girlfriend says ok and walks away. Then Anthony savagely eats a handful of french fries. (
Anthony and Jenna he's cheating with are sitting on a bed making faces at each other. When they are done, Anthony says, "Whoo! All right, that was great. See you later." Jenna whines, "But you didn't mentally cuddle with me!"
Do It In the Dark
Anthony says, "It's not cheating if you can't see who you're doing the cheating with."
He steps into a darkened closet, and asks, "Where are you? Oh, hey!" Then he and an unseen girl start making out, and Anthony states that she's a really good kisser. His original girlfriend's voice says, "Of course I am!" Anthony is at first confused when he hears her voice, so he turns on the light to reveal that he was kissing his real girlfriend the whole time, and he screams, "Gross!"
("CHEATED ON YOUR GIRLFRIEND WITH YOUR GIRLFRIEND!")
Hide Your Secret Lover
Anthony's real girlfriend says goodbye to him and says she loves him. After she walks away, Anthony knocks on the door to a closet and says that "the coast is clear." An apparently gay man comes out of the closet saying, "Yay!" and Anthony screams in horror. (
"CAME OUT OF THE CLOSET!")
No Physical Contact
Anthony says, "If you have something preventing skin-to-skin contact, it's hardly cheating."
He turns around to ask Jenna who he is cheating with if she's done wrapping herself with plastic wrap, only to see her fully wrapped and lying dead on his bed. Anthony admits, "Guess I should've poked some breathing holes."
Do It on a Leap Year
Anthony and an older lady are getting dressed together, and Anthony says, "Well, see you in four years!" The older lady says, "Wait, where's my present? It's my birthday today." Anthony answers, "So technically, I just did it with a ten-year-old?" She answers yes, and they both throw up.
Anthony says, "Your girlfriend will have no idea that your real self is out with someone else."
He says to his clone, "Now I can cheat all I want." His clone answers, "Good luck, Anthony." His real self says, "See you later, Anthony. Nice hair." He starts to walk away when he realizes he forgot his phone. He turns back to get it, only to see his clone and his girlfriend making out. He shouts, "What kind of terrible girlfriend cheats?!" With tears streaming down his face, he says, "I'll hate you forever." (CRY BABY!)
Build a Robot of Yourself
Anthony says, "One good way to get around this is to build a robot replica of yourself, with built-in parameters preventing it from making out with your girlfriend."
Anthony spins the dial on the robot, from "REALLY NAUGHTY!!!" to "NAUGHTY" to "SOMEWHAT NAUGHTY" to "MORMON." He pushes the ON button, and the robot comes to life.
It shows Anthony's girlfriend and the robot sitting on a couch together. His girlfriend says, "Oh, you're the best, Anthony." She turns around to perfect her makeup. Anthony adds, "The only downside is the slight chance that it becomes sentient." The robot is now brutally murdering the girlfriend with a chainsaw and blood spewing everywhere.
Anthony says, "If all else fails, come clean. Cheating is probably one of the worst things a human can do, aside from genocide and marrying a Kardashian. So if you're really interested in someone else, you should probably just tell her the truth."
He turns to his girlfriend and says, "I'm sorry, but I've been seeing someone else." She answers, "Whatever, I've been seeing somebody else too." Anthony asks, "Who?" and Sgt. Anous pops out from behind a plant, admitting Anthony's girlfriend is now interested in him. Before Anthony can say anything, his girlfriend says, "Wait! Today I've learned that cheating is never the answer. We should've taken the time to address our issues instead of turning to the comforts of other people. Had we just taken a little time to communicate, this would have never happened. Anthony, I am so sorry. I'll never cheat again." As Sgt. Anous grows bored during the girl's speech, Anthony agrees. Sgt. Anous says his catchphrase, "BULLS**T!" and starts shooting Anthony to death, even holding his gun with his feet at one point.
After Anthony dies, Anous says to his girlfriend, "Now that that guy's dead, you can cheat on him with me forever!" Sgt. Anous' girlfriend (who for some reason has a mustache exactly like her boyfriend's), pops up from behind a potted plant, and yells, "Stop right there!", catching Sgt. Anous in the act of cheating on her. Although Sgt. Anous claims that the situation is "not what it looks like", his girlfriend screams "BULLS**T!" and shoots the Sgt. Anous with her gun, and then with her mustache. (
Instead of Sgt. Anous shooting Anthony to death, he instead shoots Anthony's girlfriend. Then, Sgt. Anous says to Anthony, "Well, now that she's out of the way, what are you doing tonight sweetie?"
(HE'S BATTING FOR BOTH TEAMS!)
Early in the morning the day the video was to be released, Anthony tweeted two different thumbnails, asking which one would you most likely click. 
In HOW TO DUMP YOUR GIRLFRIEND!, Anthony's girlfriend states that Sergeant Anous is her father. If they are the same girl in both videos, then Anthony's girlfriend would have been cheating with him with her dad.
The scene "Do it on a Leap Year," took place after Anthony had sex with the woman, whose birthday was on Leap Day, which is February 29th. He states that, technically, he had sex with a 10-year old. If you multiply her "Leap age" by four [Leap Day only occurs on Leap years, and Leap years occur once every four years, except on years with numbers divisible by 100 but not 400, you would end up with 40 years. This means Anthony had sex with a 40-year old, technically speaking. People might consider it abnormal that Anthony did have sex with someone who is 15 years older than him.
The girl that the thumbnail says to "CHEAT ON HER" is the girl that Anthony cheats with not on.
This episode's thumbnail has differences with the El Smosh one, the English one has Jenna making a weird face, the El Smosh thumbnail has Jenna making a happy face (with a mustache drawn on it).
There is an L poster from the popular manga/anime series Death Note during the "No Physical Contact" step.