haha this is a funny question, but here's a few things you can say!
- i wasn't feeling well (honesty is always a good option)
- i was unable to make it (leave them to guess, you truly have no obligation to tell them anything)
now if you want to bluff to get them off your back, try:
- family stuff
- had to babysit a sibling that wasn't feeling well
- i overslept (lol)
hope this helps! and don't stress about it too much, everyone needs a break. if they pry, just remember it's your decision to tell them whatever you want, and you shouldn't be in trouble for staying home when you're just not feeling it.
feel better!