look up any word, like plopping:

1 definition by ian "salty sea dog" evans

When one has "followed through" or just simply shit there underpants (undies).. shity undies="sundies!"
"Oh fuck no!, ive just farted and shit my fuckin myself! Im gonna have to go change these fuckin sundies!"
by ian "salty sea dog" evans September 05, 2007