What's the best way for a husband to encourage his wife to be intimate with other men?

Tell her it's all a part of experimenting with different things and if she doesn't like it she doesn't have to do it again. Assure her that you love her and before doing this she needs a lot of emtional support from you. If she's the type who goes to church on Sundays you need to assure her that it is not a sin and that you totally approve. Good luck!