In the UK, I've heard pants being used as slang for underpants (or was it in Bridget Jones' Diary?), whereas in India it almost exclusively means "trousers".
Describing the meaning of "put your pants on one leg at a time", this link says:
To say that someone puts their pants on one leg at a time means that the person is a human being no different from anyone else.
The idiom's origin seems to refer to trousers but I'm wondering whether someone reading this might think "underpants" rather than trousers?