Tent

A tent is a type of sleeping accommodation usually used on vacation. Sleeping in one restores a Sim's energy.

The Sims: Vacation
Tents are one of the lodging options available on Vacation Island. In the default lots, they will be found in the forest and beach areas.

Tents rent for 79 simoleons a night, and two Sims can sleep in one. When Sims who are sleeping in a tent wake up, they automatically change into the appropriate clothing for the area of Vacation Island they're in. Just having a hotel key doesn't allow Sims to use tents, but Sims that have hotel keys can rent them. While Rental Shack Zack talks of "checking out" when a tent is rented, what appears to happen is that the rental expires at 11:00 AM.

The Sims 2 Bon Voyage
A tent is a type of accommodation in Bon Voyage. Similar to Igloos from The Sims Vacation. It can be bought in buy mode under Comfort > Miscellaneous.

Sims can sleep and WooHoo in a tent. Sleeping in a tent gives the Sim a Vacation Memento.

Sleeping in a tent on vacation is free.

The Sims 3 World Adventures
Tents are where a Sim in a basecamp sleep. They are rabbit holes.

There are 3 kind of tents to buy. The first is the basic green one, called Sim Scout's Classic Camper and costs §220. Second is like a little house with two bedrooms, called Colesim 2Br edition tent and costs §2700. The third is called Sultan's Tabernacle and can only be purchased from the special merchant using ancient coins. It requires a level 3 visa to purchase.

Sims can find tents at general stores in Al Simhara, Champs Les Sims and Shang Simla but can also buy them in community lots everywhere which have a General store cash register (including Sunset Valley and Riverview).