Whether you want to tell someone off or you want something sucked, chupar is your verb of choice. Let's starting with giving someone a piece of your mind.
You can also simply say:
That works pretty good, and it's equally as rude in Spanish as it is in English. But if you want to be a little more specific, just tack on the body part in question.
Chúpame las bolas
Suck my balls
While the word bolas works pretty good, there's also a few other words for balls.
In Mexico and probably a few other countries, huevos means balls.
Chúpame los huevos
Suck my balls
You can also use the words cojones and pelotas.
Chúpame los cojones
Chúpame las pelotas
They all mean the same thing, so take your pick. Trust me, you'll be understood no matter what country you're in.
Pelotas, cojones and bolas aren't the only things that can go with chupar. Here's another very popular expression.
Chúpame la cola
Kiss my ass
Chúpame el culo
Suck my ass
Truth is we could translate either of the above as kiss or suck my ass. After all, is there really a difference? It's the idea we're after.
This is where we get to the part about you wanting something sucked. You can use chupar to tell that special someone exactly what you want.
Quiero que me chupes
I want you suck me
That's a literal translation. Figuratively it would be more like "I want you to go down on me". It's one of those things that doesn't necessarily translate all that well, but I think you get the idea. And yes, you ladies can use this too.
Quiero que me chupes las tetas
I want you to suck my tits
¿Te gusta chupar pinga?
Do you like to suck dick?
This time it's not an insult, and it works for guys and gals. Your partner will know exactly what it is they need to do.
Roberto empezó a chuparmela con su lengua
Robert began to go down on me with his tongue
I'm not sure what else he could be using, but hey, who am I to judge?
Chúpame la panocha
Suck my pussy
Panocha is a very Mexican word for pussy, but substitute whatever word you need for it and you're golden.
I think we've run out of things to chupar. Take you're new found knowledge and go have some fun!