It would be my dumb luck, if I happend to be standing behind him too nervous to say anything or disrupt him...and my stupid cell phone with it's various FotC and EvS ringtones would go off loud as can be.
THEN I'd really feel stupid!
It might happen.
I just think of them as normal guys. They still pee with the seat up (probably), have whatever habits that others might find a bit gross or unattractive.... normal people.
The thing is, even though they are well known in many places now, I don't consider them 'famous' or 'celebs'. They certainly don't put themselves out to appear that way. They are just unassuming and nice to people.
I've never been one for approaching anyone remotely well known when they are on their own time though. I'd not like my privacy invaded while having a drink or some such, so try to leave others alone. I may chance it if a person was waiting for a bus or sat next to me on a train, but if with friends or looking like they were doing something, I'd leave 'em be.