Why all the whistling at Christian Lell?

So last night at the game between FCB and 1860, anytime FCB's Christian Lell had the ball, the 1860 fans would make an obnoxious, high-pitched whistling sound. No one in the group I was with knew the exact reason, although one said she believed Lell had previously been with TSV 1860 and was considered a 'traitor'. However, I just checked his stats, and he only played for Bayern and Köln, so her reasoning is out.

So, does anyone know why?

Dunno if it was the reason, but it would be a pretty good reason:

Bayern star hit his girlfriend (German link)

yes, this has been well documented. He was picked up by ther police from the FCB training Hotel the last time it happened.

My 1860 boys told me that Bayern paid off the girlfriend. He's a wife-beating mofo who got away with it because Bayern have the money to silence people.

He never played for 60. Apart from a loan period to Cologne (2006) he has been with Bayern for a good few years. He was living in the house we bought in 2006 after just coming back from Cologne and we spoke to him a few times during the viewing stage (I didn't know who he was before that). He struck me as being a pretty normal bloke but from what I've read since he must have a screw loose...