From Homestar Runner Wiki
A few times here and again, some of the characters in the Homestar Runner Universe show poor sportsmanship. Such can include yelling at other characters, cheating, or other. The Cheat has shown this by, of course, cheating mostly for Strong Bad. Although this has occurred often, it's mainly from Strong Bad and The Cheat.
- Original Book — Strong Bad insults Homestar and Pom Pom by saying they're not strong. The Cheat unplugs The Robot and helps Strong Bad hold his grapes.
- A Jumping Jack Contest — The Cheat and Strong Mad work together to sabotage the contest in Strong Bad's favor.
- Tis True, Pom Pom, Tis True — The Cheat knocks Homestar out with a baseball bat, thus letting Strong Bad win the King of Town's 100 Mile Superthon.
- A Jorb Well Done — Pom Pom apparently gets mad and bounces on Strong Sad's stomach at the beginning during their game.
- The Reddest Radish — Strong Bad, Strong Mad and the Cheat steal Marzipan's radish to help him win the contest, as well as fake a message from Homestar, so that Marzipan would not show up for the contest.
- Strongest Man in the World — Strong Bad insults Homestar and Pom Pom by saying they're not strong. It is implied that Pom Pom swears due to Homestar's and Strong Bad's reactions. The Cheat unplugs The Robot and helps Strong Bad hold his grapes. Homestar Runner gets angry at Pom Pom for not giving him the trophy saying that he "sportsmanshipped" the most.
- Email strong badathlon — It is said that the games celebrate drug testing and "poor sportsmanship".
- Email pet show — The Cheat sabotages the other contestants to help Strong Bad win, but is disqualified when Homestar puts relish on Strong Bad's foot.
- Email hiding — Strong Bad pretends to hide but doesn't to fool Homestar, and then Homestar Runner gets mad when the Robot Strong Bad "sasses back" at him.
- Homestar Ruiner — Strong Bad cheats big time during The Free Country USA Tri-annual Race to the End of the Race by: stiffening the water, putting a balloon (a really powerful one) on the weight, and moving the objects in order from Biggest to smallest so he could finish on time and win.
- Baddest of the Bands — Strong Bad sabotaged all the other Bands within the "Baddest of the Bands" contest so he could win.
- Dangeresque 3: The Criminal Projective — When playing Rock, Paper, Baccarat, Perducci stacks the deck so he always draws the ace of spades. Dangeresque then steals the ace of spades and the rock from the table so he can beat Perducci.
- Kick-A-Ball — Strong Bad accuses Homestar Runner of cheating. When Homestar Runner's team said, "Good game", Strong Bad's team said in reply, "Yeah right."