I am rarely snappy. I am always afraid of offending people, and fear the consequences if I do, so I rarely snap at people even when it is justified. Also my dad was very snappy as a child and it used to upset me a lot, and I don't want to make people feel the same way as that made me feel.
There are some occasions where I can be a bit snappy though. If I am tired, or feel emotionally exhausted in a social situation, I might appear rude and abruptly leave with a very stern goodbye. In another scenario, I might be really interested in something and explaining something I feel passionate about, and someone might interrupt me, or say something incorrect on the subject, and I might rudely shoot them down. But this sort of thing happens very infrequently.