armar

A very common, versatile verb: to arm (with weapons), to assemble or put together (armar un mueble, a piece of furniture), and, colloquially, to stir up or cause something disruptive (armar un lío/escándalo, to cause a mess/scandal).

• El gobierno decidió armar a las fuerzas de seguridad con nuevo equipo. — The government decided to arm the security forces with new equipment.
• Tardamos dos horas en armar el armario del IKEA. — It took us two hours to assemble the IKEA wardrobe.
• Los vecinos armaron un escándalo por el ruido de la obra. — The neighbors made a huge fuss over the noise from the construction.

Missing the colloquial, non-literal sense — armarla or armar un lío doesn't involve any actual weapon; it means to stir up trouble or cause a commotion, a very common figurative use.

• expression Armarse la marimorena — Widely used Spanish expression, recognized by the RAE, meaning to break out into a loud fight or uproar. It traces to a documented 1579 tavern brawl in Madrid's Cava Baja involving a woman known as María Morena, whose name became fused into the fixed phrase.