What do you call the sound the microwave does when it's done cooking? A ding. Granted, the sound you get when gaining a level is more like Brrrrrwwwwhing, but we call that a ding too.
Of course I guess you could say: "Hey, chaps! I just gained an experience level"
Whereas someone in your group would go "Congratulations!" To which you would reply: "I am laughing out loud", and you would have merry-good times, but the time gap between pulling packs in dungeons would increase radically.