I haven't seen the series in a while, so I'm a bit fuzzy on the exact scene details, but basically:
"follow me, and your urologist will be buying himself a new yacht."
Dr. Lisa Cuddy is warning House, that if he follows or stalks her, that she will hit or break his balls/groin so bad that he will have to see his urologist so much, such that the urologist will be able to afford a new yatch.
So basically, like Colin Fine said, it means "if you follow me, I'll break your balls." Or something to that effect. The indirect and clever way some of the House retort/dialogue is worded is one of the awesome things that I loved about the series.