Hoult was barely 13 when he played Grant's son in the hit comedy, and since the Golden Globe winner was well-known as a charming ladies man, the young actor watched his every move to learn how to conduct himself around women.
He tells Elle magazine, "Just watching him was quite remarkable. He's one of the most charming people in the world. Women do just melt around him. There was kind of, 'Oh, okay. He seems to have something.'"
The actor, who recently split from his girlfriend of two years, Jennifer Lawrence, also got a lot of advice from his two sisters.
He explains, "My older brother left home when I was fairly young and my father (a pilot) was always away a lot, so I was raised by mum and my sisters. So I can maybe steer clear of some pitfalls that guys who didn't grow up with women would fall into.
"It's more the awareness that whenever they leave the house they will be half an hour later than the time they said it would be - you know, additions in timing. And to never jump in a shower after a girl's been in there. It's guaranteed to be scalding hot."