When about to have sexual intercourse, rather than easing the penis into the vagina, you yell the word "thunderslam" and you slam your penis home hard and dry.
Dude did you hear it last night, I heard David yell thunderslam and a few minutes later I saw Shanaynay walk out pissed and hurting.
by J-Lew71 April 27, 2006
Thunderslam is an term created to express an hard hit or the feeling of getting hit hard with a certain feeling or sensation.
by Sir Slangalot August 8, 2009