What goes on in Vegas most certainly will NOT stay in Vegas here!
Watch it go down (below)!!!
Check out the pic of them (above)!!!
As we mentioned, Si's other ex girlfriend, Sinitta, is on the trip with them, too (below)! Wonder which one he kissed at midnight…???
Boy, he definitely treats his former flames like royalty!!!
Such a playboy, that Cowell! LOLz!
[Image via FameFlynet Pictures.]