TEFLees in Spain

This recently happened to one of our TEFLites, Kate, in her business English class:

Scene: 9:25 am, the end of class. Marcos and Isabel, both in their mid-twenties, are the only two students today. Marcos is wearing a t-shirt that says, “I’m not losing my hair, I’m getting more head.”

Kate: Ok, we have a couple minutes left, so let’s talk about Marcos’ shirt. Marcos, could you tell me what it means?
Marcos: (looking at her like, ‘aren’t you the English speaker here?’) Um, i guess it means that my hair is suiciding [sic], and because of that my head is getting bigger. Like i have more head now, right?
Kate: Right, that’s the literal sense, but it also means something else. Do you guys know what a double entendre is?
Isabel: Yeah, when a word has two meanings.
Kate: Right. So the phrase “getting more head” is a double entendre in English. What do you think it means?
Isabel: I don’t know, maybe that he’s losing his hair but he’s getting smarter? Like, more head means smarter.
Kate: Um, no. Ok. “Getting head” in English is slang for having oral sex.
Marcos: Wait, what?
Isabel: (laughing)
Kate: So when it says “I’m not losing my hair, I’m getting more head”, it means that even though you’re going bald you’re having more sex.
Marcos: (shrugs) Well, it’s the truth.