My girlfriend wants to tie me up and tickle me. What should I do?

Ok it's been about 4 months that I've been with my girlfriend and it's going really well but now she's starting to ask me to do some really weird things. She wants to tie me to a bed and tickle me. I don't know if I should do it or just say no or something else. Plus I'm really ticklish so I don't think I would enjoy it much but should I do it for her? I guess it's harmless. Does anyone know why she might want that and have any advice for me?