Everyone had assumed that Tony Stark and Steve Rogers was a "thing". Always arguing, always trying to play leader for the team, always watching out for the other, the list can go on forever. But, they didn't like "like" each other.
Thor and Steve had a secret thing. No one on the team knew, and when Loki magically reappeared, and much to Thor's surprise, in front of the couple making out. Well, lets just stay at the fact that the god was somewhat surprised.
They were good at keeping the secret, even Loki. Steve was afraid that the Trickster might spill with his little games, but Thor was confident his little brother would keep the secret. Of course Loki would try to leave hints and try to get the team to notice, but to no avail. They were just that good.
Well, one day, Tony heard someone grumbling and talking to someone else then a squished noise. Curious he was, he asked Jarvis to bring up the security cameras and what he saw, well, let's just say, somewhat lewd.
He stormed into Thor's room, where him and Steve where lip-locked on the bed. Tony made an "ew" sound then yelled out "LEWD".