Now about the grand and noble old sport of Tiddlywinks, or even, Extreme Ironing??
No, not tiddlywinks, pedallywinks! You know that ping when you accidentally squeeze a bit of loose road chipping into the side of a car alongside, pedallywinks would be played in public car parks, with golf balls, and with points awarded for setting off burglar alarms, cracking windscreens, etc. Bonus points for front wheel pings (offs count like refusals in horse jumping). Top score would be when you manage to ping a black Golf (because in my neck of the woods, they're far too often the ones blithely trying to ping me off the road).
I'm assuming, of course, that the OP already has a bike. The only expense would be buying a few golf balls. (Unseasoned conkers are too soft.)
There's also a polo version of this game but it's not as satisfying as ''Audi0,'' where you get off 0 by pinging Audis.