I actually made one up once. The "4 Fs" for VFR diversions for the private checkride (before the days of GPS).I think mnemonics should be appropriate to the situation…for example
LAND-
Lower the gear
Assess fuel settings
‘N set them appropriately
Decrease prop pitch
of course, all emergencies would be “OH ****”, so that confuses things.
Find it
Figure it
Fly it
Fine tune it
There's actually a fifth F before the others - it the one you say out loud you come across the need to divert, but I didn't think we needed a mnemonic for that!