You may not remember the Whose Line guys having to put a heckler in his place before. This is why.
It's not so much "heckler" than "some guy who wanted to yell "Freeze!", but the way the cast make fun of him and sit on him is also a Funny Moment.
Colin scores a personal one in one session of "Options" - when the style called out is "horror", he messes up his own hair (what there is of it) and executes a Jekyll-and-Hyde-esque transformation that catches everybody off guard.
In Episode 22's game of "Options" featuring Drew and Jonathan, someone yelled "William Shakespeare". As per American Whose Line tradition ("The sky. The sky, it is bluuuuuuuuuuuuuuuuue!" anyone?), Drew completely failed to think of anything - but Jonathan immediately began to monologue in an affected dramatic accent for almost half a minute straight. When Jonathan paused to allow Drew to respond, Drew took too long, and Jonathan bellowed, "SPEAK NOT; WHY DON'T THOU SPEAK?!" and continued monologuing.
And then, when Chip accidentally cut him off with a "freeze", Jonathan paused, waiting for the next option, and Chip told him to keep going. So he did.
Episode 25's jazz song to Belinda was funny, but more importantly, it showcased the incredible singing talents of Chip and Jeff. Jeff consistently sounded like Michael Bublé for most of the song, and Chip finished the song with a high note so crisp that Jeff double-taked.
Colin's impromptu Russian type dance in Bob's Call in episode 32.
Chip's Monologue in Episode 35's Forward/Reverse had the audience cheering, and then when Jeff called Reverse he still got all of it right!