lewd but technically true
@pearshapes your dick(s), if you have any
@pearshapes also a car's suspension, or a bus's air brakes
an automatic transmission is also basically an entire hydraulic computer, especially older ones
drinking through a straw probably counts as a combined hydraulic/pneumatic system
some types of car jack are hydraulic or pneumatic
re:// lewd but technically true
@Felthry tragically, no dicks here