The (lack of) logic.

Overheard in office today:

[phone rings]
A: Hello.
B: Hello, is Mr Tan there?
A: Sorry, Mr Tan is not around.
B: But his mobile phone is off, so he must be in office.
A: !?!?!?!?!?!?!

someone seems to be lacking in logic here.

(all names have been changed to protect the guilty illogical)