Relatively small amounts of beer, depending on the dog’s size, will kill it.
In 27 years in the veterinary field I’ve never heard this or seen it but grape/raisin toxicity was unheard of until several years ago so I looked it up. Some dogs can have a sensitivity to hops which may cause a malignant hyperthermia. If they are sensitive a small amount could be dangerous but the biggest risk would be for home brewers that use hops or if you grow the plant where the dog could get hold of whole hops. This does not mean that a few laps of beer will kill any dog, but it is always a good idea to keep any alcoholic beverages away from pets. Sniffing beer caps or licking the tops of beer bottles isn’t likely to be a problem for the OP’s cats.
Usually he just licks a few drops/sips off of my uncle’s hands. And this isn’t really frequent. They really don’t feed him beer or alcohol on a regular basis.
No offense, but do you have a cite for this? NOT that I doubt you that alcohol is unhealthy for pets, but what do you mean by “small amounts?” (We’re talking about a Brittany spaniel)
Now see here, she has a tragic DISEASE and needs to go to kitty rehab! … My parents had a cat that loved beer, they’d pour a little in a saucer for him. Then he’d go sleep it off. Though it was hard to tell because he was an old cat and slept most of the time anyway.
http://www.vetinfo.com/dog-alcohol-poisoning-beer.html
http://www.chacha.com/question/what-happens-if-dogs-drink-alcohol
Sorry about being so curt. I’m the kind of person who would a football helmet on my dog if he played chess.
Maybe you have a smart cat. 
Barbara cat knocks over empties to lap up a few drops, he will also dip his paw and lick drops out of glasses, and if he gets enough beer he goes on a tear all over the house. He also really seems to like his Brewer’s yeast nutritional supplement, and begs for it like a treat. I support the “filthy drunk” hypothesis.
A twenty-four step program perhaps? 
Hmm, never noticed any of my cats going for beer (or any alcohol). One of our cats has taken to drinking coffee if you don’t watch your mug, which is kind of a pain to have to worry about since I assume it to be really unhealthy for a relatively small cat to be lapping full drinks out of a coffee mug.
My dog, however, loves beer. He’s a 90 pound Weimaraner, so I don’t worry too much about giving him the last few drops from my beer bottle (literally – you know when you “empty” the bottle, but if you turned it upside-down a couple more drops will fall out – that’s what he gets). He goes absolutely nuts for it, licking madly at the mouth of the upturned bottle. Those petting zoos with the baby goats that you can feed from a bottle – yeah, that’s him. CUTE! I rinse everything before it goes into the recycle bin, so I’ve never had a problem with anyone raiding the bin.
Because beer is good.
Given that a lot of hairball remedies and cat toothpaste is “malt flavor”, I’m guessing cats like the flavor of malt.
Does your cat eat pizza, pretzels, hot wings, or peanuts?
I have two that will eat pretzels if you let them.
I would assume that the danger with alcohol would be the vast difference in size between a cat and a human, no? If a cat weighs a tenth of a person, isn’t drinking a beer the same thing as a human drinking ten beers?
I know a tiny bit of ethanol would easily “knock out” tiny critters in bio labs I’ve done (don’t worry, I’m talking things like worms, not cats).
I once got my dog drunk on purpose, it was 4th of july and he was one of those dogs who cannot handle fireworks and my parents left him with me and no doggy drugs.
we weighed him and I think it ended up being 1/3 or 1/4 cup of beer. funny funny funny stuff, then he passed out and enjoyed his 4th of july in doggy nap land.
no noticeable harm done.
Q. Can a cowboy’s dog get a driver’s license?
A. No, but the cat’ll drive.
Beer is proof that God loves cats, and wants them to be happy.