Is it appropriate to give my friends dad a card with money in it for his bday?

I have not known my friends dad for super long, and he is always getting me a card with money in it for holidays or my birthday. He really appreciates me being a great friend to his daughter and it shows. He also invites us out to eat from time to time and he always pays the bill. I want to get him a card and put some money in it for his birthday as well, do you think this will make him feel weird in any way? Or should I just get him a card with no money in it?