when someone “gets hitchhiked” it basically means that they got thumb-fucked in their vagina. instead of getting fingered with the pointer/middle finger, the person fingering them opted to use their thumb instead. this comes from the known-symbol for hitchhiking—a thumbs up.
After being anally fucked in missionary by your partner or significant other, you then get picked up and worn like a backpack. Meanwhile, your partner or significant other fucks a tiny dwarf bitch reverse cowgirl.