Longman Dictionary of Contemporary English
sponge bag
noun
EXAMPLES FROM CORPUS
▪ He had a quick look in Dale's sponge bag.
▪ It's like being zipped into a sponge bag - yuck.
▪ She took her sponge bag into the bathroom, expecting something primitive, and paused, surprised yet again.
▪ When that final whistle went I just wanted to throw up in the sponge bag.
Wiktionary
sponge bag
n. (context UK English) A bag of toiletry.
WordNet
sponge bag
n. a waterproof bag for holding bathrooms items (soap and toothpaste etc.) when you are travelling [syn: toilet bag]