I love these for my bloody marys. They add a vinegary zing and I will even eat them straight. I haven't really found any other use for them but I always have them in my fridge. Sometimes they can be a little difficult to find but my Walmart thankfully carries them.
Whenever my mom and I would buy the veggie mix, we'd fight over the cocktail onions. Now that I'm grown, I bought a whole jar of the onions and love them! They can be a tad spicy sometimes but oh so good and vinegar-y. I haven't tried using these in cocktails yet; I just eat them straight out of the jar for a tasty treat.