For what kind of sexual play exactly? Are you melting it and licking it off? Sticking it inside someone (please no...)?

Personally I like chocolate as much as the next dyke, but to me sex is a savory pursuit. Sweet is better left to before or after.

There are a lot of chocolate flavored things that are safe and fine for things like foreplay, but I would avoid getting chocolate inside of any orifice that isn't a mouth.