When I was still running air, I used to nick ballons from the parties I took my kids to.
But I've gotten with the times and run Mousse in my tubes. My mate who rides a BM swears by Swartzkoph styling mousse, but he's a squareheaded airhead. I just raid whatever the missus has in the bathroom, and always carry a spare can on the bike in case I get a flat. Doubles up for helmet hair as well.