I love [adjective / noun] + [noun] URLs, so that's mainly what I use TBH [i.e. prettygf / ryuutogf]! I'm sorry I can't help more! I'm honestly pretty lazy when it comes to usernames. You can also come up with shortened [mthrly] or slightly misspelled [pitjful / pitif-l / mwaid] usernames too ... I find repetition users too [vivixen / ssscythe] etc ... I don't know if any of these examples are taken, by the way!