How can I best display a three-way toggle (show, show all, and hide)?

I'm creating a filter for a search and I am wondering how to best approach this interface.

I have a bunch of events in a database and my website displays certain events based on the user's criteria. That's simple enough, but some events have notes on them, like they serve alcohol, or you have to be over 18 to attend, or it's for women only, or something like that. What I'd like to do is add to my "search" form some way of representing and toggling between these options.

This will be more than just on and off, since I also want them to have the ability to ignore these as well. In this case, if I turn 18+ off, does that mean it will actively hide all 18+ events, or that it just won't show only 18+ events? It gets confusing for the user.

To give the user all options and make this as clear as I can, I'm thinking a three-way toggle is best: OFF - This setting ignores the 18+ note and displays events normally. SHOW - This setting shows only 18+ events. HIDE - This setting ignores all 18+ events.

IF I were to do this, I'd have to also consider layout. Will this be a three-way switch? Will it be a grid where there are three checkboxes? Will I have to turn "on" an 18+ search criteria and then select "on" or "off"?

If I did a three-way switch, how would I design it? How would I name it so that it's clear one setting just ignores the 18+ altogether, while the other two exclusively show or hide these events?

This is where I would like some assistance. Have you seen something like this before on a website (or other interface) where this was done particularly well? Can you offer any advice?

Thanks!

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(A bit about my background - I'm a huge UI guy. I have a Master's in it, I do it professionally, and I've even taught some college courses in it. This is my first post here. Hello all!)