"BUY 1 FREE 1" joke

A MINI MARKET IS DOING A PROMOTION.. BUY 1 FREE 1.. 1 CUSTOMER CAME IN...
OWNER: WELCOME... WE ARE DOING A PROMOTION BUY 1 FREE 1..
CUSTOMER: IS IT TRUE..?
OWNER: YES OF COURSE..
CUSTOMER: THEN GIVE ME THE FREE 1...