Wash Your Mouth, or Tricky English (Part I)

Actual conversation:
Me: "What do you eat for lunch?"
Student: "I usually eat soap."
Me: "Soap? You eat soap for lunch? Or do you eat soup for lunch?"
The half of the class that is paying attention erupts in laughter.
Student: "Oh no! No! Soup! I eat soup for lunch!"

This is a common mistake when going from Spanish to English, or vice-versa.

soup = sopa; soap = jabón

The problem when learning English arises in the food chapter, while the problem when learning Spanish arises in the "you should" lesson (accompanied by health/hygiene suggestions).

I remember this conversation from my Spanish class in high school:
Yo: "Se debe lavar tus manos con la sopa."
Profesora: "¿Sopa? ¿Lavas tus manos con la sopa? ¿O lavas tus manos con el jabón?"
Todo la clase rompe a risa. 
Yo: "¡El jabón! ¡Se debe lavar tus manos con el jabón!"

Joder. False cognates are a bitch.