Which would be the translation to Spanish of
I have a crush on your sister.
When speaking Spanish, everybody uses the English word and I'd like to know the translation.
The use of the word
JoulSauron is right to mention the colloquialism of those expressions, as neither of those are used in Mexico (they may be understood in the right context, but I've never heard them being used here). However I'd use:
Which may or may not be used in other places as well...
Some phrases we use in Spain for "crush":
As these are colloquial, I'm guessing in other countries they use other expressions. Definitely, not everybody uses the English word, actually I would say just in few countries is used "crush" in Spanish.