How to ask your partner to have a threesome?

Many people ask me how to ask your partner to have a threesome with you. This is a question which is asked by many swinger couples. If you do not know how to ask properly, it can leave your partner a impression that you are just tired of having sex with him/her and you want to have sex with another person.
You can say to your partner that you want to watch him/her have sex with another person. You think it is very hot. In this way, you don't have to involve yourself in. There will be no such mistake.