Basically 1 followed by 100 zeros.
Coined by E.Kasner who also coined the Googolplex
which is a googol multiplyed by a googol
Guy1 "I think i'll count from 1 to a googol"
Guy2 "ok guess I'll see you in heaven"
Guy2 "Because it will take your whole life to even come close to counting to a Googol"
Guy1 "ohhhhh, well how about a million?"
Guy2 " (sighs) cya in about 15 years then"
Guy1 "But i thought..."
Guy2 pulls out a pistol and shoots himself
Guy1 "Was it something i said?"
Guy2's dead body shoots himself again twice.