"Funny" in this context means strange or odd. "It's strange that you should ask me about that." You would use it when somebody asks about something and your immediate response is "what a coincidence!" "I'm thinking of buying an iPad - do you know any place where I can get one cheap?" "Funny you should ask. I'm thinking of selling mine. Are you interested?"

It's saying you should've ask before doing something, usually uses (by another person saying it to you) after you made a mistake.I think that's what it means

意思有一点儿像“真是太巧了”似的。