I am someone who is very good at "reading between the lines" and who has a very good understanding of sarcasm, yet I have a tendency to take jokes and sarcastic comments literally at first. My issue is that I am slow to get things. It just doesn't register right away, but after a few seconds I get it. My understanding is that this is different from people on the autism spectrum not being able to understand sarcasm, jokes, etc.

Don't know about your friend, but I would be pretty offended if a friend pointed out that I have trouble getting sarcasm or jokes. I would interpret that as them saying I am slow. I would start to question why they want to be friends with me if they think of me that way.