Yes, I'm sure the slugs in your garden will be delighted to drown themselves in it. And if it's not terribly out of date, it might even still be drinkable. A lot of consumables are still OK after their "Best by" date.
I used to know a cook who made the best batter for fish That I have ever tasted. She said her 'secret' was stale beer. Not so much 'out of date' but rather beer that had been sitting opened for a couple of days.
Beer is usually pasteurised during the bottling / canning process. Although it more than likely will not have gained or lost any strength due to it not having any additional yeast added the taste will more than likely not have altered either, my advice, get it down you. If you do have any worries use it to replace water in gravy / yorkshire pudding batter or sauce recipes. Extra heat can only kill any bugs! Enjoy!!!!!!!!!!!!!