i would suggest getting lots of carrots and sticking them on sticks, you can either eat them or sell them. also you should buy some ducks, they can make really good freinds. or if you want to be really crazy go out drinking with your ducks and eat carrots on sticks while you're drinking vodka with carrot juice.
Clubs are for idiots. I don't take the OP for an idiot. To give real advice... go to a dive bar or something like that with some close friends and then finish the night off with a house party. That's what I'd do.
Hit up a pub with all your boys and girls, get nice and loose, then head out to the classiest strip club and town, do a couple of lines of a urinal, then head back to your place for an all nighter filled with tequila shots, Journey sing-alongs, fingerbanging and drinking games. that is if you want to celebrate your 21st by doing what everyone else does.
My 70 year old aunt slingshotted a thong from one of those guys at her grand daughter (my second cousin) while driving her to school one day. I have to think that the whole scene is wack.
Create a grand plan and have a brainstorming session with trusted friends. Or just do something you enjoy.
go to vegas! i wanted to go to vegas for my 21st, but my friends bailed and i spent all my money in europe i wanna go to vegas so badly