[flashback to two weeks before Marshall and Lily's wedding:]
Ted: Marshall, what are you doing?
Marshall: Going to the bathroom.
Ted: In the hall?
Marshall: Sleepwalking?
Ted: You're wide awake.
Marshall: Robbing us?
Ted: Dude.
[back to the wedding:]
Ted: [v.o.] Turns out, all week long he'd been sneaking out to a hotel on 72nd, to meet Lily.