Do celebrities inroduce themselves?

So, I was watching the Golden Globes a couple of years ago, and Julia Roberts came on stage as a presenter. She had been seated next to Paul McCartney, and she said she's never gotten more texts in her life. I have never forgotten the question I asked myself after that. Do celebrities introduce themselves to other celebrities? I mean they already who each other is. Are they like "Hi I'm Julia Roberts, What's your name?" They already know who they are. Is it bad etiquette, though, to just assume that people know who you are. I mean, you celebrities can't really go up to another celebrity that they've never met and be all "Hi Paul, I've never met you, but you are a celebrity so I know who you are. I know you know who I am." That is rude.  I still don't know. I suppose celebrities meeting other celebrities would be a little awkward, because they don't know what to say to get the conversation started. I guess I'm lucky not to be a celebrity in this case.