Oh BOY. Let's hope they're just friends?

We spotted Lindsay Lohan partying until 7AM at Jason Segel's house, and earlier in the evening (er, morning?) we saw a blanketed partygoer leaving, but alas, it was a Lindsay impersonator.

In the video above, you can see Lindsay bouncing around the room with a cigarette hanging out of her mouth (she's wearing the white winter hat), and even though they're not in a bathroom, we have to wonder what was going on in there!

Is Lindsay hooking up with the Sarah Marshall star? Or are the two just close party buddies?