IN AN ENGLISH PUB: "HOLA! QUIERO UN OSO!"
There is no getting away from the fact that the words "beer" "bear" and "beard" are pronounced very similarly. It seems obvious for a native speaker, but they are hard for Spanish speakers.
"Beer" and "bear" are often confused, and therefore you get the strange situation where the bartender is wondering whether you really want a "bear"!?
Try to practice these words with your English teacher. You need to get to the point where it feels very natural.
Hope that helps!
Soy el director de Daniel Smith + Partners. Tengo más de 10 años de experiencia enseñando inglés a españoles.