Mine actually has to do with horseback riding (jumping). It was already my youtube username and I was too lazy to come up with a new one But I guess it works because jumping could apply to gymnastics and dance also!
Mine is based off my personal e-mail address that I let my youngest daughter help me come up with years ago. CO= Colorado, terp=interpreter, guide=raft guide, girl. I moved to CO from Quebec way back when I was in junior high, fell in love with the mountains and have lived here ever since. Also two of my jobs include raft guiding and being a sign language interpreter. Kind of a mouth full I suppose, but it works!
Many years ago, computers couldn't handle files or usernames longer than 8 characters. Policy at my first job was first six letters of last name, first initial, middle initial was your username. Been using it ever since. Works out fairly well, as I never have anyone else take this name on a website, so I can always get it when I join some site.