If you’ve never tried it, a sixer or 12pack of something good (ie, not a domestic light) may get your derailleurs adjusted and cables tensioned next time you only need wheels trued. But the beer drop-off has to seem unsolicited and with no-strings attached – and definitly not when the shop owner is around, unless s/he is also your beer-drinking wrench. A clue to whether this is even OK is if the shop has a mini-fridge. Odds are there is either beer in it now or has been recently. It needs to be done while dropping the bike off for service, not when you are picking it up to pay for it (unless you already know the guys and have done the ol’ beer bribe before). Even better would be to drop it off when you’re just looking around. My LBS is next to my grocery store and I know the shop guys. I’ll buy a 6 or 12, early season, and say, “Hey this was on sale. See you later.” It means when I drop it off for a tune-up I may get an extra bolt or two tightened or something looked at which is usually included on the premium service menu. Beer doesn’t include parts or extensive labor, like rebuilding a headset or repacking bearings. I’m not expecting a Campy upgrade or threading internal cables for a sixer of Bud Light.