When I worked at Briggs and Briggs music in Harvard Sq., Alan Ginsberg walked in one day. I didn't let on that I recognized him, but helped him look for a CD of an early British composer.
"He was a contemporary of Shakespeare, wasn't he", I asked.
He told me otherwise.
"You're the poet, so you should know it", I said.
What followed was the most intense staring contest of my life with me holding to my joke and he refusing to laugh!