How to Say "little monsters" in Spanish
The Spanish word for “little monsters” is “bichos” — B1 level.
English → SpanishB1
nounB1informal
playful but annoying kids

Examples
Tus hijos son unos bichos, no paran quietos.
Your kids are such rascals; they don't sit still.
Describing people
When calling people 'bichos', you usually use the word 'unos' before it (unos bichos) to mean 'some real rascals'.
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