I don’t get social cues

I thought I was fine socially. That people just called me socially awkward because I don't do the same things or wear as them, I didn't really care until it hit me today. I tried to ask a guy for his snap (first time), my friend joked that I should do it and I took it seriously. I did and apparently said some weird things? I had another friend by my side, she is much younger but understands society really well. When the guy began laughing and giggling at me I said something horrendous "Not with a romantic intention" after all I did it for her. Him and his friend laughed even more. I didn't understand what I did wrong. I looked more mature than them, but we are the same age, how come they laughed at me? I thank about it over the night, why did they laugh? I thought my sister was bad at reading social cues, but I guess I am even worse. How can I get better? I don't realise when people use irony or what I should say, and it makes them look down upon me.