Something I always like to do versus Caro Kann players (who aim for a solid middle game setup, is frighten them with this:

Plan:

1. Castle on kingside

2. Push f-pawn for open rook file on king

3. Push g-pawn if you cant push f-pawn

4. Push h-pawn if you cant push g pawn to push f pawn.

5. Get open lines

6. Mate the black king.

Pro's: 

1. You get a strange, wild position, especially in the dreadful Caro Kann.

2. Caro Kann players panic

Con's:

1. Black should be able to defend if played correctly. 

2. You might insult your opponent if he likes solid play (but then again, thats why you pick such a line, hue hue hue hue)

Example games:

http://www.chess.com/livechess/game?id=379425478

http://www.chess.com/livechess/game?id=379529662

Most fun in blitz.

if you want as crazy but more sound, try either h4 over bd3 or play nc3 and answer e6 with g4.