For someone who won't stop nagging

Dar la lata

dar lah LAH-tah — To be a pain / nag

"Mi hermano pequeño me está dando la lata todo el día."
My little brother has been bugging me all day.

Literally "to give the tin can" — nobody's sure exactly why, but it's a very common way to complain about someone being annoying or persistent.

"My mother used this on me constantly as a teenager. Fair, probably."— Graciela