What's the informal word for a small challenge?

Example:

I challenge you to get her number. If you get it, you earn a beer.

It's sort of a friendly bet. It's a short 3-5 letter word. I've heard it but can't recall it. Please help.

Something pertaining to: bet, challenge, dare, play, sport, game, toy.

May also relate: a clever move, trick, stunt, tactic.

Solution 1:

A word I've heard used in this context is a wager, which TFD defines as:

An agreement under which each bettor pledges a certain amount to the other depending on the outcome of an unsettled matter.

In this case, the unsettled matter is whether the lady will give the challenged party her number. The challenger is pledging a free beer to the challenged party; if the challenged party accepts, they are pledging to get her number.

Given the casual nature of the bet, this might even qualify as a friendly wager, a phrase whose popularity is shown in this nGram plot.

Solution 2:

Dare seems to be the right word to use in this case. It may not be the actual word you are looking for but it certainly fits very well:

to tell (someone) to do something especially as a way of showing courage

Source: Merriam-Webster

I dare you to go to her and get her number. If you succeed, I'll buy you a drink!

I have only one reservation that dare plus a reward is not inherent in what I feel is the original meaning, however wager seems so old fashioned, and I would likely use dare myself if I wanted to challenge a friend to go on a dare even if I would add the extra reward to the successful completion.

If you google for dare you her number you get

• First, Chris dared me to ask the girl in line at the movies for her number.
• One night his friends dare him to ask for the dark skater girls number
• "Try to get her number....... We Dare You." (Nike ad)

The word bet already suggested is a better word if your friend will have to buy YOU a beer if he does not succeed

Solution 3:

I defy you to get her number.

Per Meriam-Webster:

defy: to challenge to do something considered impossible

Solution 4:

A deal

noun 1. An agreement entered into by two or more parties for their mutual benefit, especially in a business or political context
Oxford Dictionaries

When the Op states that it is a word related to a game or sport, perhaps he was thinking of a card game where each player is dealt a hand that consists of several cards.

A synonym for the word challenge is a test. The Free Dictionary defines it as:

A series of questions, problems, or physical responses designed to determine knowledge, intelligence, or ability.

There's also the term test match

a game or series of games of cricket or rugby played by teams from different countries
Merriam-Webster

Connected to the expression bet which is often heard in the world of sports and games alike is stake

Sports & Games

a. Money or property risked in a wager or gambling game. Often used in the plural. See Synonyms at bet.
b. The prize awarded the winner of a contest or race.
c. A race offering a prize to the winner, especially a horserace in which the prize consists of money contributed equally by the horse owners.
T.F.D

Its plural form, stakes, is commonly used in the game of poker. Wikipedia says:

All casinos and many home games play poker by what are called table stakes rules, which state that each player starts each deal with a certain stake, and plays that deal with that stake. A player may not remove money from the table or add money from his or her pocket during the play of a hand. In essence, table stakes rules creates a maximum and a minimum buy-in amount for cash game poker as well as rules for adding and removing the stake from play.