Here's my 2 cents worth:

To help sort out jig rhythm I use pineapple, pineapple
For reel rhythm, watermelon, watermelon

I don't have a good mnemonic for hornpipe rhythm...yet...

Jigs are further subdivided, at least in Irish music

There are single jigs, which sound more like "humpty-dumpty". There are also slides, which are a subcategory of single jigs and often written in 12/8 instead of 6/8. No good mnemonic there yet either...

And slip jigs can also be divided into the ones that sound more like double jigs (pineapple, pineapple, pineapple) and the ones that are more like single jigs (humpty-dumpty-dumpity)

That last group of slip jigs are sometimes called hop jigs, but not among Irish step dancers who have a completely confusing alternate set of terms for all the dances except reels and hornpipes.

Sharon