A truck with either, extra large wheels, raised body, smoke pipes or a combination of all 3 which are driven by guys (possibly women) who have small dicks. One's need to impress ladies is done with the ridiculous truck size that attracts attention away from the lack of size in other places, or place. Thus compensation trucks are used exactly for, compensating.
Dan: I just bought this new truck, it's raised. Im hoping that girls won't notice my small dick as much anymore now that i gots this HUGE truck!
Joe: Dude, that shit works soo well, my truck gets all the ladies. Im buying smoke stacks, here cumm the ladies ;)
("Ladies" walking by)
Lady 1: HA HA HA! Look at those stupid compensation trucks...LOSERSSS
Lady 2: We all know what they're compensating for.