The only correct response to the question “Can I ask you a question?” is “You just did!” Literally!I cringe when I hear that crap. And yeah, "Can I ask you a question?" ranks up there with the same level of stupidity. Why don't you just ask your question, it would have taken less than half the time. What's even worse, if you answer no, they ask anyway.
Then hit them with...it's literally "MAY I ask you a question" not "CAN I ask you a question".