I have cut my "20 fingers"! I am not good at "hand jobs"!

This conversation happened when I was still living in Brazil. I was having a private English class, and was having a conversation with my teacher. I was telling her what I did the day before, and it led me to say one more pearl of wisdom.

This was the conversation:

J - I did my manicure last night. 
T - Oh nice. 
J - Not too nice, I have cut all of my 20 fingers.
T - 20 fingers? interesting.. 
J - It's sad! I am not good at 'hand jobs'!
T - Really?
J - Yeah
T - Do you know what you just said me? That you were a monkey, and you weren't good at male masturbation. 
J - What???
T - Yes, just monkeys have 20 fingers, humans have 10 fingers and 10 toes. And hand jobs is a slang to male masturbation, you should have said that you weren't good at working with your hands.

We laughed a lot after that. 

Typical case of "watch your mouth'.