1. 'To put your toe in the water' means to test something, to very carefully have a look, or try something out.

a. When I first started my podcast, I put my toe in the water of internet projects, and slowly realized that I can do this!

b. It was his first teaching job; he taught three days a week. So as he put his toe in the water and got experience, he decided that he enjoyed the career.

2. 'To show off' is to brag, to proudly display yourself or something you have or you can do.

a. The little boy showed off his new toy car to his friends; they all thought it was very special.

b. Don't show off! It's irritating! So you can walk on your hands, big deal! I can walk on my feet.

3. 'I can't read your mind' means that you should communicate clearly. It can also be a direct translation instead of an idiomatic phrase.

a. When you ask me to get you something to eat, can you be more specific? I can't read your mind, you know.

b. It's weird, she knows what I'm going to say before I say it. It's like she can read my mind.