Follar

Adding to the other comment, “joder”. Closer to fuck as a curse word.

What the two other guys said, but clarifications are needed.

• “Joder” is mostly used for verbal attacks, cursing or to express frustration.
• “Follar” is mostly slang for having sex.

However, there are execptions, as you can say both “que te jodan” or “que te follen” to say “fuck you” to someone in Spain.

Bonus way to say “fuck you”: Que te den por culo = Get fucked in the ass

Why am I having so much fun explaning these?