Your son crapped his pants.
I smell it. You smell it. The woman at the front desk at this kiddie gym smells it. Hell, the whole party smells it. So why are you letting your son continue to jump on the trampoline with a full bowl of pants pudding?
Perhaps something is wrong with your olfactory system. Still, can't you see everyone picking up their child as they jump by you, smelling their butts and then sighing in relief that it's not their kid with the trouser chili?
Are you waiting for your wife? Fair enough, I, in fact, pulled that this morning...Bud dropped a deuce (actually, it was more like a deuce-and-a-half) right around the time mommy was about to take over...why should I go through the trouble of changing the diaper? (No such luck, though, I lost odds-or-evens, 2-to-1.) In any event, there's a time limit for letting your kid sit in fudge tracks.
Your son crapped his pants. Please change him.