I made this activity for a conversation class for adult students, so you may need to alter it to suit your needs. I would say that decently advanced high school students could also do it without a lot of problems.
The premise of this is similar to the shows "Shark Tank" or "Dragon's Den," if you've seen those. Apparently those shows were based on an old Japanese TV show called "tora no money," so if your students are familiar with that, they'll get the premise.
First, every student needs to come up with a business idea. I introduce the verb "pitch" at this time in the context of a business pitch. It can be a serious proposal or something a little more silly. I assign each student in the class a letter, which they should write in the section at the top right of the sheet. They should fill in as much information as they want about what kind of business it will be and how it will make money.
While they're writing, I distribute small pieces of paper to each student. I usually make them by taking a sheet or two of A3 paper and chopping it in the paper chopper a couple times until I have a lot of matchbox-sized cards.
Once everyone's about ready, I ask the students to present their idea to the class. They should say which letter they are, and then the listening students will take notes using the section on the second page. In a large class, you may need to make another page for this, or have students work in groups so there aren't too many proposals. My class was 12 students and that's probably about the number of proposals you can hear in one sitting without it taking too long.
Once all the proposals are given, I ask the students to write the letters of the two pitches that they're willing to fund. I have them give the cards to me face down and then shuffle them. I tally up the results on the blackboard then to find the final champion!