Caerte el veinte, is a phrase you say when you finally get the meaning of something, like a joke, or something from school, after having trouble understanding at first. Its also used when someone sttuborn finally stops with his or her stubbornness, and starts doing as said.
Ya le cayo el veinte, Ya se hizo la vasectomia, y ya no va a tener mas hijos por doquier. / He understood already. He got the vasectomy and now he wont keep on having children everywhere
Entonces, esta formula resuleve este problema? – Si, parece que ya te cayo el veinte. / So, this formula solves this problem? – Yes, seems you finally are understanding.
I hope you have learned something new, about the spanish that real Mexicans talk on their everyday life.
If you want to improve your Spanish, I also give tutoring lessons on skype using this page that host many teachers from all over the world, and while I don’t really do grammar, I can help with conversation and doubts about the language. Also, if you are interested in any language besides spanish, there are teachers and tutors for any language there.