Imagine Steve seeing Bucky wearing some sort of Captain America-branded merch for the first time. (Whether it's super subtle or, like, Hot Topic with rhinestones.)
Bucky comes down to breakfast wearing boxer shorts with the Captain America shield emblazoned on the ass and...nothing else. Steve’s eyes nearly bug out of his skull.
“...Bucky?” he says after a moment, watching the play of his muscles as he reaches up to grab the cereal box and pour it into a bowl. Bucky grunts, still hardly awake. Steve is sure that Bucky went to sleep last night fully clothed, but he can’t stop staring at Bucky’s ass.
Bucky looks up with a mouthful of cereal, cheeks bulged out and long hair in a messy bun. He swallows his bite. “What?”
“Um,” Steve can’t help blushing and curses his fair skin. “Your, uh. Your boxers.”
Bucky glances down. “Huh, would you look at that.”
Bucky arches an eyebrow at him. Steve flushes furiously. “...why?”
“I like ‘em?” He shrugs. “Maybe I like having you on my ass, Stevie.”
Steve makes a startled sound and Bucky doesn’t stop grinning the whole breakfast.