(v.) to add additional gasoline to the gas tank even though the gas tank container is full. People do it to get the most bang for their buck, to have more gas in their car. This action can be dangerous and it is prohibited by most gas stations. Most gas station attendants do it anyway to sell more petroleum.
To ejaculate massive ammounts of semen into a vagina or anus. This practice can only be accomplished in the absence of condoms or any other contraceptive that prevents the exchange of fluids. A vagina that has been habitually been topped off runs the risk of becomming garbage pussy.
Bend over whore, Im gonna top off your gas tank with pure, unadulterated eastern Kentucky baby slime.