Here are some left over ideas from when I was brainstorming for the concept. Feel free to borrow, steal, or modify any of these ideas if they jump out at you.
5’s Contest
-5 finger death punch
-5 finger discount
-5th element (the movie)
-5 senses (touch, sight, hearing, smell and taste)
-5 love languages
-5 finger Monk
-Gimme 5 (based on hand slaps/high 5s)
-Take 5, subclass based on bonuses while taking a short rest