The classic Green slime trigger phrase has always been... "I don't know."

But if you were to ask someone "Do you want to get slimed?" and they were to respond "I don't, No." Would that also qualify?

It works better for comedy if homophonic words/phrases trigger it!

I think this might be "canon" already, but I agree that it should work that way regardless for comedy's sake. The gag is more effective when it can be used in new and unexpected ways, and the fact that it's not necessarily "fair" is part of the appeal.

100% yes

I hoped you'd approve, I had this notion whilst watching "Kelli's Slime Time (with Her Daughter Britney!)" There's a moment where it almost happens (but doesn't quite) and I realized I'd never seen this particular trigger situation brought to life before.