The only thing the orphan learned from his dad is the hide-and-seek skill to hide for 18 years. He tried it out; now he has infinite milk.
Professional Hide and Seek
Explanation
Explain Bear
Listen up, tiny brain. The kid's dad 'hid' for 18 years, meaning he abandoned him. The kid tried to 'hide' too, and since he's now a missing person, his face is printed on milk cartons. That is why he has 'infinite milk.' You're so slow you probably still think your dad is just at the store buying cigarettes.