Go to a festival

You knew a small festival was around in your neighborhood. It was a really laid back festival where they offered theatre, food and drinks and other kinds of entertainment. You were going there every every summer since you were little. Today is a really sunny day so I think it would be a nice place to test out my new wishing power.

Once you get to the festival there are already some shows going on and you just decide to sit at a table and order a drink.

Then you think of your first wish.

"I wish all girls here would wear cute dresses with bright colors and no underwear underneath at all."

You look around you and all the girls were suddenly really wearing dresses with no exception at all.

Wow you thought to yourself this wishing actually works!