Situation: You are with a friend and you explain to him/her that María, a mutual friend of yours, is pregnant. Your friend asks you whose is the baby. You are surprised that s/he doesn't know, because everyone knows that it's her boyfriend's, Guillermo's. Tell him/her that the bay she's getting is Guillermo's.
Semantic interpretation: Statement of the obvious.
Speaker: ACR
Utterance: ¡Pues de Guillermo!
Translation: It's Guillermo's, of course!