Back in university days I often wrote assignments while tipsy and then edited them when sober. Cider was just perfect for silencing the inner critic to get some thoughts to paper.
From what I understand, there's a substantial body of research indicating that a slight suppression of the prefrontal cortex can reduce the sorts of inhibitive filters that constrain creative thought. Too much, obviously, and you impair your cognitive ability. Too little, and self-doubt and over-analysis rules.
Anecdotally, I've noticed that I'm significantly more fluent in my third language when I've had a drink or two. I get many, many more compliments. When I'm totally sober, I tend to trip up more and overthink the grammar.
There are lots of ways to reduce a hyperactive prefrontal cortex, including training (practicing art, meditating, etc.), but alcohol is by far the cheapest, quickest, and easiest.
Everyone has some skill they insist they are "better at" when drunk.