Looking for group Game Suggestions w/ minimal or no req'd parts

Hopefully the Title explained it all.

I’m looking for games that can pretty much be played anywhere, because you don’t have to have a game board, etc. Maybe just a piece of paper or something easily obtainable wherever you might be.

I seem to remember a game talked about here before that was something like a spy game? I’m fuzzy on the details which is probably why I couldn’t find it online. Something like one person is a spy in the group, and the purpose of the game is to figure out who the spy is?

One of my favorite quick & easy games is “I have a number.”
The object of the game is guess (or NOT guess) the number.
i.e. whoever guesses the number, has to buy the next round of beers
or everyone starts off by throwing in a dollar, and whoever guesses the number collects the pot.
The Rules:
(recommend you track on a piece of paper) Moderator writes down a number between 0 and 1000, and covers it up.
Player next to the moderator guesses a number between 0 and 1000.
Moderator says “high” or “low.”
Next person then has to guess a number in that range, narrowing it down even further.
Continues on in this fashion until the number is guessed.*
*Moderator plays too… they must take the next number closest to the secret number.
i.e. 4 people playing, number is 187
Person 1: “500”
Mod: “That’s high, that leaves 0 to 499”
P2: “200”
Mod: “That’s high, that leaves 0 to 199”
P3: “100”
Mod: “That’s low, that leaves 101 to 199, and that means I have to take the next closest number, which is 101, and P1 has to pick a number from 102 to 199”
P1: “150”
Mod: “Low, that leaves 151 to 199”
etc, etc.

What I like about this game is the inclination to pick a number closest to the edge of the range instead of in the middle; somehow believing it’s ‘safer’. Generally picking a number in dead center is the best play, as it narrows down the overall field of numbers. This is especially true if you’re playing where whomever picks the number loses the game.

What fresh ideas do you guys have to offer?

Celebrity

Exquisite Corpse

Telephone Pictionary

Mafia

This looks like Mafia, which I came in to suggest, but I see Inner Stickler has beaten me to it.

There are plenty of drinking games that fit this description. 2 simple ones (that you can make more complex by adding more “rules” as you go along, if desired) are Fizz buzz and 21. For the former, you can make it a bit more complex by using 5 and 7 (instead of 3 and 5) for “fizz” and “buzz”, and also insist number containing the relevant number are replaced by “fizz” and “buzz”.

This would lead to such as: “…48, buzz, fizz-fizz [for being a multiple of and containing the number 5], fizz, fizz, fizz, fizz-fizz-fizz, fizz-buzz, fizz-buzz, fizz, fizz, fizz, 61…”.

Well, there’s Botticelli. Er, I mean this link.

charades :o

rocks paper scissors

psychic wars

Noel Coward-like battle of wits.