The contents of a container or something being transported. Can refer to the cargo of a truck or other transport vehicle as well as the semen located in the male testicles.
"The payload in that truck weighs several thousand pounds."
"I busted a fat payload of cum on that bitch's face!"
A sexual maneuver in which you hold your partner aloft, initiate a standing sixty-nine, and then pile drive them during the act, with your genitalia still in their mouth. Typically, this move is announced using pseudo-military terms.
"Get ready, sweetie; ordinance has been deployed. Preparing to deliver the Szechuan Payload."