and it means someone doing something against his own belief or law just for some benefit.
also,"sell out" got some brother meanings, "sell out some things"means starting to sell some items or sell it in discount.
15. Februar 2010
This means to side or support somebody because of money or a favor being given, even though it goes against one's stated beliefs.
It can also be used as a noun - "sellout"
"Many of the people in the politician's district thought that he had sold out to the big tobacco companies when he voted to support tobacco subsidies."
"His vote was considered a sellout."