I first learnt about the risks of mixing pineapple with gelatin from Casey and Andy. Basically, pineapple contains the enzyme bromelain, which breaks down the protein that makes up gelatin, rendering it ineffective as a jelling agent in food preparation. So if you mix pineapple with your gelatin, you'll end up with a gooey mess. This only applies to fresh pineapple, because canned pineapple is heat-treated, which breaks down the bromelain.

The other point about this strip is that I used the term gelatin dessert rather than the British/Australian English term jelly or the usual American English term "Jell-O", which is a trademark and not a generic name. Normally I use Australian English, but in this case I wanted something that at least meant the same thing to all readers, rather than simply using "jelly", which would have meant something completely different to American readers.