Random question about ABV.

The other day, my boyfriend and I went to his mom’s house and they had over a couple of their friends. One of them mentioned they had 10 Twisted Tea Lights, the ABV is 10%. So I was like “Well that’s about 40% then” and my boyfriend’s mom’s boyfriend was like “no…that means 4% of your body weight” or something along those lines. I work in a liquor store and asked my manager but she seemed confused but was leaning more towards me because how would they know the body weight lol? The 10 Twisted Teas at 4% x 10 would mean he took in 40% alcohol, right?