I'm in the Office
This phrase is a lie. You're actually in the bathroom, probably trying to hide the fact that you just ate a whole bag of chips and your pants are now a second skin.
'I'm in the office', you're in the bathroom, and your pants are now a second skin.
'I'm in the office', you just ate a whole bag of chips and you're trying to avoid a pants disaster.
'I'm in the office', you're trying to hide the fact that you're wearing your mom's old pants.