Technically, this comic has two punchlines. 100 points to anyone who guesses the second punchline.
Uh-oh, this makes the plot page obsolete, since MK will be an important character for this. Oh well, that thing used old sprites as well and didn't have the Pegasus Boots.
I would consider that the main punchline; you need to guess both.
Wait, if Green and you are the fastest, how did Red get there first?
Or is that punchine numba two?
That's not a punchline at all, we're just not on camera; Ruby arrived a bit after us.
Is it MK pointing out their sudden seriousness?
TGYR, you win 100 points.