For me here are some things I've done while hypomanic:
-overcommit myself because I think I can handle it, but of course when I become depressed again it's wayyyy too much (ex: enrolling in 18 hours while working two jobs and an internship)
-stay up all night (or only sleep a couple hours) doing something random that I suddenly feel is very important, like a research project
-make impulsive decisions like cutting my own hair, having sex with someone I've never met, going on shopping sprees, go on spontaneous runs (usually in the dark in an unfamiliar neighborhood with no planned route and no lights or reflective clothes)
-spend wayyyyy too much money
-talk a lot, usually an annoying amount