Absolutely! In the F6 menu, going to player and player skin will give you a bunch of options on how to add and remove clothing and generally look quite silly.
The F5 menu has a lot of the same stuff as well as I think some stuff the F6 menu doesn't! (though the F6 menu is way better for cars use it) In general, just flick around and mess with your character until they look like you want them to. Once they look just right, go to the F7 menu and select ped, and save your character. Now every time you join the server, you'll look like the cool rad racer that you are.