My boyfriend wants me to swallow but I've never done it?

My boyfriend is really freaky when it comes to sex but there are certain things that I'm uncomfortable trying that are new to me such as swallowing cum. I gave him head an I was about to try it but I refused so I spit it out like wtf I'm not a porn star lol that was nasty. He's not forcing me to do it but one day when I'm ready he wants me to try. Any of you ladies swollowed before? Is it nasty does it turn you on? I won't judge I promise I just want to know from experiences.