Bolted onto the underside of the tail end of a skateboard, the tail guard (also known as a "skid plate") protected the tail end from skid stops and other maneuvers that would otherwise wear away the wood (commonly known as razor tail) and decrease the longevity of the tail. Typically made of plastic, these were widely popular in the '80s but their usage quickly diminished with the arrival of two-tail board designs, which became increasingly popular in the '90s.
Smile and wave – Feel free to look around at all the other people at the skatepark that stood by and marveled at your new-found accomplishments (all one of them). I’m sure by this point you’ll be picking up roses that are being thrown at your feet, and taking a well-deserved bow as they begin to chant your name. Take it all in, thank the crowd for their undying affection, and then go get a snow-cone. You deserve it, champ.