If Popbitch is to be believed she's having threesomes with her 2 bodyguards.
They're a pretty reliable source and normally if it's libellous they'll couch it in non-libellous terms, but no, here's the text from the weekly Popbitch email in full.
''US newspapers claim to have a story that Chelsea Clinton has been getting, er, serviced by her two Secret Service minders. At the same time. The man and woman appointed to protect the ex-First Daughter are said to be in trouble for taking that to mean they should get this up close and personal with their charge. So far the threesome are keeping quiet but with US service personnel getting blown up on a daily basis, shouldn't we just be happy that some of them are just getting blown?''