1. This was part of a longer fic, I think possibly Steve had been giving Bucky a blowjob or using his hands on him and had gotten distracted before he was fully undressed because he'd come in his underwear. The phrasing that stuck in my mind was Bucky laughing at him as he grimaced/pulled a face "at the rapidly cooling mess in his pants". It was just a hot, light hearted moment between them.
2. Steve fucking Bucky with an icicle. It might have been set during WW2 and they were later reminiscing about it, or it might have been post-CAtWS, but Steve had been nervous about it and had Bucky suck & lick the icicle (which had been snapped off the eaves of the building they were staying in) first to make sure it was smooth and safe to insert into his backside. (Possibly Bucky was initially blindfolded?)
Edit 11/5/16: Found #2, it's from the Yes, Captain series. The actual sex with an icicle happened during the first story, the reminiscing happened in the second part!