narices
/naˈɾiθes/ · B1 · adv
the heck
👃 Literally noses: ¿Qué narices? = what the noses?, a polite swap for a ruder word
Narices is the plural of nariz (nose), from Latin naris (nostril), the same root as English nasal. In ¿Qué narices haces? it's a mild euphemism standing in for a ruder word, a lot like saying what the heck instead of swearing.