What you need

Ten paper or plastic cups of the same size for each player. A flat surface. A timer.

How to play

Give each player a stack of ten cups, mouth down.
On "Go", each player builds a pyramid with four cups in the bottom row, then three, two and one.
As soon as the pyramid stands complete, the player takes it down again, sliding the cups back into one stack.
Cups that fall may be picked up and replaced, but the clock keeps running.
A player's time stops when the single stack is back on the table with both hands off it.

The fastest time wins. In a race between two players, the first to finish wins.

Bigger: fifteen cups in rows of five, four, three, two and one.
Team relay: one member builds, the next takes down, the third builds again.
One-handed, or with a balloon held between the knees, for people who have found it too easy.
Tower: who can build the tallest free-standing tower of cups in one minute?

Use paper cups you can reuse for serving water later in the party, or recycle afterwards.

Flimsy cups stick together. Separate and loosen every stack before the game.
Disputes about who finished first. Race two at a time, each with a judge.

Time the round with the party timer, make chits or random teams with the chit maker, and keep the points on the scoreboard.