One's brain, or, more specifically, one's collection of memories (and capacity for additional memories). An allusion to the notion that one's mind is like a sponge.
cf. hard drive, floppy drive, thumb drive
"I can’t remember much more... Hard drives nearing full. Sponge drive doesn’t work so well for digital assets."
I’m not a cum bucket…but a classy Seaman Sponge Receptacle.
Someone who, when participating in a conversation, chooses to say little no words, generally because they have nothing interesting to contribute.
That guy was a real word sponge, he didn't say a single thing.
A product that has been over-engineered for a too specific purpose. A product is usually considered to be a left-handed sponge when it is marketed with a very specific purpose, yet another cheaper generic multi-purpose product can easily be used in its place.
Did you get some chain lube for your bike? Nah, it's a left-handed sponge. I just use WD-40.