Disclaimer: Don't drink and drive. The driver must be the designated sober driver. Be creative on how this person is chosen (e.g. perhaps the overall loser of last weekend's drunk fest.) Also, beware of areas with "open container" laws. There's nothing like being stopped by the local sherriff of some backwoods town along the way and being told "You ain't from 'round here, are you, boy?" then spending a night in the slammer.
This is a simple game, with a low to moderate buzz factor, depending on the oil output of the region traveled through. You know those see-saw type oil pumping rigs? Keep an eye out for them on your next road trip. They dot the pastures along the interstate in rural Texas, Louisiana, Oklahoma, and a number of other oil producing states. If you see one that is pumping, pump with it, that is, take one drink every time the "head" end bobs up (the part with the rod attached that goes down in the well). If there are many around, pump once for every one you see. If you see one that is not pumping, pump FOR it... Take a drink anyway. And if you see a tall drilling derrick, raise a high toast and chug what's left.