Some of them have holes between stalls where guys insert things. Otherwise you go under the barrier, or just use the same stall.
Why would you want to meet people that way, when there are community organizations, churches, bookstores, pride festivals, museums, art galleries, and any number of more comfortable places?
And if you meet someone in a t-room, why not take them home? T-rooms are gross and uncomfortable, and people could interrupt you at any moment. Not to mention the risk of arrest for "lewd behavior."
But, in the fall of 1996, my friend David, who cruised constantly in bars, bathhouses, public parks, and public restrooms, talked me into giving "tearoom trade" a try.
The rest of the story is too risque for Boomer Beefcake and Bonding; you can read it at Tales of West Hollywood.