A fork of Rural Dictionary
The reserve of sexual images or thoughts used for masturbation. Similar to a gas tank, but imaginary and naughty.
"Did you see that girl's tits?"
"Oh yeah! That's some definite fuel for the spanktank."
When you slowly and continuously fill a fish tank with your semen, take a microscope, and watch the dead sperms float around.
Tyler: Yo dude have you been filling your spanktank.
Vincent: Yeah mang it's filled to the brim with my little swimmers.