Often there's less alcohol in the "wet garbage" than in the "girly drink." Plus, the extra sugar in the girly drink accelerates the effects of the alcohol.
The other oddity about "masculine" stereotypes of drinks is that often the color of the drink comes into it. My favorite drink is called a Negroni:
As you can see, it's red. This has occasionally led people to believe it's a "girly drink" based on looks alone. When they bring it to their lips, they're quickly disabused of that notion. A Negroni is equal parts Gin, Sweet Vermouth, and Campari. It's all alcohol, mostly high proof. It's also bitter as fuck. But some people would refuse to drink it, not because they think it tastes bad (though many people hate the bitterness), but because it's red. It's silly.