A beer.
The default friendly word for beer. ¿Vamos por unas chelas? is the standard invitation. Related: a michelada is beer with lime, salt and sauces, a whole order of its own.
Probably from michelada, or from chela as a nickname for a fair-haired person — the colour of a lager.
Casual. In a formal restaurant just ask for una cerveza.
Reading a definition isn't the same as saying it to someone. Lingo Kaiava is a voice tutor set to Mexican Spanish — it uses chela the way locals do, corrects you in the moment, and never "fixes" the way real people actually talk into textbook Mexican Spanish.
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