Arthur looks, if you'll pardon the pun, so fucking serious when they're in bed. He's got his eyes shut and he's sucking Eames's cock intently, his cheeks hollowed. Ariadne's busy letting Eames suck a hickey onto her neck, but she keeps looking at Arthur, and she keeps having to bite her lip to keep the laughter in.

All at once, Arthur looks up at her as Eames bites her hard, and it all spills over, her laughter bubbling out everywhere.