Huh?

Conversation between hubby and betu a while back -

Hubby singing the song "Sweety sweety tera pyaar chahida..."

Betu: Aap kyun yeh gaana ga rahe ho? Aapki to biwi hai. Aapko girlfriend thode hi chahiye. Aapki biwi naraaz ho jayegi agar aap girlfriend le kar aayoge.

Me: *dumbstruck*...at usage of word "Biwi" (wife) and also at his understanding of the fact that either biwi or girlfriend.