Automatic bicycle pump
Low on air? Steal some from a car. Well, that’s the idea anyways. I am not sure a car’s tire pressure would be able to sufficiently pump up a bicycle tire because car tires are run at lower psi, but it is some food for thought.
Go here to find out how to make your own, and when you do, let me know if it works!
Take your bike and go find a hummer (or some other overweight vehicle). Fold the hose in your hand so you don’t waste any precious energy. Attach one end to the automobile tyre and the other to your bike. When you unfold the hose you can hear a hiss. That is the sound of air flowing to your bike wheel and the world becoming a better place 
Fold the hose again before you detach it from both vehicles.
via instructables
Tweet
shit like this is what makes car drivers feel justified in their animosity for bikers.
this trick will not fully deflate the car tire btw.
Don’t forget the fact that car tires are only filled up to about 38 psi tops. And they’ll more than likely be lower in the cold winter months. That’s less than half what’s recommended on road bike tires and even shy of MTB tires. Could be good for getting home on a flat, but not “topping off”.