Jim's bent over the back of the couch, fluffing the pillows he's got set up just so while he hums along to the music. Really, he's not trying to look sexy (he wouldn't have one lag stuck out all wonky like if he was). Felix just happened to catch him while he's nitpicking details.

"Everything's all ready for y--yah!" Jim was mid-holler back toward the kitchen when he finally straightened and turned around and startled at Felix being behind him. "Shit man, don't scare a guy like that."

Or maybe do, if the laugh he's got crinkling his eyes at the corners is any indication of how pleased he is that Felix has come back to join him.