Spanish has a lot of ways to refer to stupidity. Below are some of the most common ones.

Aguacate – stupid in Costa Rica
Baboso – a slobbering fool
Bruto – stupid or rude
Burro – donkey or dumb-bell
Cabeza de cajón – a hollow head like a drawer
Cabeza hueca – a hollow head
Caído de la cuna – fallen from the cradle or dopey
Cerrado – stupid
Cretino – a cretin
Idiota – idiot . El es un idota (He is an idiot). Ell es una idota (She is an idiot)
Infeliz – a klutz
Jaibo – dumb in Costa Rica
Maje – also stupid in Costa Rica
Más cerrado que una bombilla – have your head more closed than a light bulb
Más cerrado que culo de mula – a vulgar Costa Rican form of the last expression
Necio – a jackass
No tener dos dedos de frente – to be brainless
No tener sal en la mollera – not very bright. La mollera is the soft spot on a baby’s head.
No tiene para un derrame – someone doesn’t have enough brains even to have a stroke
Payaso – a clown or stronger word for fool
Ser más corto que las mangas de un chaleco – to be shorter on brains than a vest’s sleeves
Simplón – a simpleton
Tarado – idiot
Tonto – fool
Torpe –  a klutz or clumsy

Tiquismo: Agüizote – is a belief or superstition. Agüizotes are also rites or rituals that are done to bring good luck for the new year. They originated in Spanish and were adopted by the people in Latin America. For example, some people eat 12 grapes at midnight on New Year’s Eve to bring them prosperity I the coming year. While others grab their suitcases and walk several times around the block in order to be able travel a lot in the coming year. Another ritual is to bathe in the closest river to say good bye to being single and find true love.  Finally, another one is to  use yellow underwear to attract good energy or red underwear to attract love. There are many more agüizotes.