I've gotten to suck off my uncles golden retriever a few times when I was much younger (~18 iirc). In the past few years tried to have some fun with a neighbors dog, but unfortunately he wasn't terribly interested as he was still young (~1.5 yrs) and larger breed (Belgian malinois). Definitely was bummed he wasn't interested as he was huge! Still a great pup though.
A guy I've messed around with had a small breed non neutered male and I was sucking the pup off while being taken from behind - definitely was hot