Garage Door 

The boss walked into the office one morning not knowing his zipper was down and his fly area wide open.

His assistant walked up to him and said, 
'This morning when you left your house, did you close your garage door?'

The boss told her he knew he'd closed the garage door, and walked into his office puzzled  by the question. 

As he finished his paperwork, he suddenly noticed his fly was open, and zipped it up.

He then understood his assistant's question about his 'garage door'

He headed out for a cup of coffee and paused by her desk to ask, 'When my garage door was open, did you see my Jaguar parked in there?' 

She smiled and said, 'No, I didn't. All I saw was an old minivan with two flat tires..