what does this joke mean?

[Mike]

the joke is. I did your mother a favor by making you a sandwhich.

or

i did your mother a favor, i made you a sandwhich.


my friend said it was a joke for teens
he told this to me when i was11 and i am 22 now. what does it mean. i still did not figure it out.

 

[Mr. Curious Rides Again]

Your friend needs to stop doing drugs, then tell the joke.

 

[Enrique]

HAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAHHAA j.p i dont get it

 

[Vampire]

i did your mom.................a favor..................by making you..................a sandwich..............

 

[Alyssa]

if you are younger than a teen, stop reading.








Example:
Boy: I did your mom... (sex)
Girl: What?
Boy: ...a favor. By making you... (making her prego)
Girl: Huh?
Boy: ...a sandwich.

 

[Frenzy Check]

I did you mother --- a favor
By making you ---- a sandwich

Weird my friend told my other friend that joke and he was one of the better kids.

 

[wwewannabe]

Its a kinda like yo momma but more of a sex joke. hope I helped