1 To sneak away and let the big poop come out Expand I'll be in my officeGoing to my office for a little breakI'm going to my office to get some business done + Examples
2 To hide from people and take a big dump Expand I need to be in my officeI'll be in my office for a bitI'll be in my office, don't bother me + Examples
3 To go to the loo and let the big one out Expand I'm going to my officeI'll be in my office for a whileI'll be in my office, I'll be back later + Examples