Hotrod Johnson is when you are feeling more than good. The night of drankin, and whatever else might have been up your sleeve to amplify the fun, may be coming to an end but not if your in your prime. Once you get to this stage in the night you have the urge to let everyone know that you are Hotrod Johnson.
To insert your penis, while wearing a condom, into hot sauce and then to proceed to enter it into a vagina. Hence, giving your lady the sensation of a 'hot rod.' Can also be referred to as giving her that "sweet, sweet Texas Pete."
Navin got a little drunk the other night and thought it would be funny to surprise his girl by hotrodding her. She was surprised alright.