I was late for work one time, because I made the mistake of turning up in the car park at the same time as this guy who had OCD.
He would:
get out car
close door
open door
close door
open close
close door
push door
open door
close door
push door REALLY hard
lock door
repeat above (no, really)
unlock door
lock door
check ALL doors by trying handles
check boot
check all doors visually
unlock door
lock door
check all doors by trying handles
check all door visually
repeat door lock routine
twice
repeat from start
twice
IT TOOK AGES.
I know I shouldn't mock, and really I'm not... but it was utterly utterly fascinating
I was entranced
I explained to my boss... well I say explained. I got as far as "There was this guy with OCD in the car...."
and he said "yep. Got me the week before!"