[xzins]

Mom, positive soul that she is, always said to wear clean underwear, ‘cause you never know if this is the day you die, and you’d be embarrassed to death if they saw you in dirty underwear.

It does make it’s own kind of sense. :>)

[redgolum]

When you die, you loose control over your bodily functions.

Your underwear won't be clean. My Dad used to be an ambulance tech, and would fire that back at my Mom every once in a while. Drove her nuts.

[zeugma]

Mom, positive soul that she is, always said to wear clean underwear, ‘cause you never know if this is the day you die, and you’d be embarrassed to death if they saw you in dirty underwear.

Except, if you pass, you're likely to soil them anyway.