In most cases, none. There could be some reaction with a chemical in a particular food that might produce a color change -- and, of course, colored liquors and liqueurs will color food accordingly.
Alcohol hurts your liver where digestion takes place. Alcohol also is just a pointless/ boring thing to do sometimes. I said sometimes, because it can be fun. But chances are you will not remember...
Narcotics, barbiturates and tranquilizers, all depressants, have similar effects. For that reason, they should never be taken with alcohol. The combined effects can be fatal.