Portuguese/Spanish word for prude?

I have a character whose moral position on sex gets him teased. His fellow inmates call him a prude, but it's something in either Portuguese or Spanish that they call him. I'd prefer the Portuguese equivalent, since the guy himself is Portuguese (I figure the insult will hit closer to home if it's in his native tongue). Anyway, what would be the preferably Portuguese or even Spanish equivalent of the English word "prude"?

Thanks guys!

Mojigato has a nice ring to it. I can definitely "see" someone spitting the word at him in a derogatory way. I'd found puritano in my own searchings, but it didn't sound right to my inner ear for some reason. I think that harder sounding "G" in mojigato sounds nastier/meaner.

Thanks guys!!!