Princeton piggy back term comes from the Princeton range of piggy back forklifts for trucks
where a small unit straddles a large truck with its forks
translates into sexual conduct with a small female riding a larger male subject with a strap on instrument also when a smaller male has infatuations with larger women and conducts intercourse
"Taking the big boy home to give him a Princeton piggy back"
"look at the jockey taking the pig home to Princeton piggy back her"