An after dinner surprise in which you expect a nice burp but end up with a little barf making its way up your esophagus thus leaving you with that horrible burning sensation. (Burp + Barf = Burf)
Earl: Gee whiz Sally, that was a fine souffle you made!!
Sally: Well thank you Earl.
Earl: Buuuuurppppblecccchhhh!! Oh Christ my thraot is burning....I just BURFED!!!
Sally: Oh Earl!!
The act of expelling an exceptionally acrid and heavy fart that feels hot in temperature, making only a slight "bfffff" sound as the bitter fumes leaves the anal cavity. Much more deadly and bitter than the average silent fart.
"Honey, you won't want to sit next me right now. This roasted garlic is making me burf."