arruncharse

A colloquial reflexive verb from the Andean region (Colombia, Ecuador, Peru) meaning to snuggle or cuddle up close to someone, especially to keep warm — arruncharse contra alguien. It's affectionate, informal, and largely unknown outside these countries.

• Los niños se arruncharon contra su abuela para ver la película. — The kids snuggled up against their grandmother to watch the movie.
• Hacía tanto frío que nos arrunchamos bajo la misma cobija. — It was so cold we cuddled up together under the same blanket.
• El gato se arruncha siempre junto a la estufa. — The cat always curls up snugly next to the stove.

Using arruncharse outside the Andean countries where it's understood — a speaker from Spain or Argentina is unlikely to recognize it; acurrucarse is the safer pan-Hispanic choice for "to snuggle/curl up."