Those sentences that cause you to trip over your words, especially when trying to say them quickly.

How much wood would a woodchuck, chuck if a woodchuck could chuck wood? A woodchuck would chuck as much wood as a woodchuck could chuck if a woodchuck could chuck wood.

Peter Piper picked a peck of pickled peppers. 

Fuzzy Wuzzy was a bear. Fuzzy Wuzzy had no hair. Fuzzy Wuzzy wasn't so fuzzy, was he?

If two witches were to watch two watches, which witch would watch which watch?

You sat across a table from your friend. The two of you were having a word war. The first challenge was tongue twisters. Whoever messed up first lost the challenge and the winner would get a point. The goal for the end of the word war was to have the most points. Another friend sat off to the side, acting as a judge.
You went first, "She sells seashells by the seashore. She sells seashells by the seashore. She sells seashells by the seashore. She sells sheshells-" you stopped realizing you had messed up.
Your friend went next, "She sells seashells by the seashore. She sells seashells by the seashore. She shells sheshe-" your friend also stopped short.
The judge came forward and explained that you had said the tongue twisters correctly more times before messing up then your friend so you took the point for the first round. You jumped up, super excited. Your friend grumbled something that sounded like 'I'll win the next one'. You laughed and sat back down, waiting for the next challenge to be announced.
To Be Continued

(A/N) I have a plan, mwahahahaha. It isn't actually sinister though, so never fear, I am here! (That was a hint to the next part ^-^) Have a nice day 😺