[thaumasiotes]

I always thought it was vaminos.

Spanish speakers are unlikely to make that mistake, though, because the ending -monos is regular for first-person plural reflexive imperatives. https://es.wiktionary.org/wiki/mirarse#Conjugaci%C3%B3n

(And -monos is etymologically very transparent - it's just the first person plural ending -mos, familiar to everybody, with the first person plural reflexive pronoun nos suffixed onto it and eliding the -s of -mos.)