Story of my life.
Aged fifteen, I was invited over by a classmate on the spur of the moment. I had not been expecting this and I felt flattered and pleased, but also surprised and awkward. Returning from a bathroom trip I said to her, "Why didn't you tell me I had pen on my face?" This was meant to tease and also to sound 'normal' -- it was the sort of thing I'd heard the other kids at school saying to one another --, but because I was feeling so awkward I delivered it in a near-monotone and with a blank expression. She looked uncomfortable, said she hadn't noticed and apologised. I realised, of course, that she had taken me up wrongly, but I felt too alarmed and embarrassed over this even to smile at her to show it was all right.
My social skills have improved a great deal since then, and I've been able to turn this problem into a nice line in deadpan sarcasm, which is much appreciated by some people though it makes others uncomfortable. The classmate who invited me over is now, some years later, my best friend, and she likes my flatly-delivered humour very much, but even so I can sometimes overdo it with her -- once quite recently I inadvertently insulted her by saying she read slowly and not indicating properly that I was teasing. Fortunately she's an easy-going person.