Hello, it has been a while. I have not thought of any new idioms to teach you. But, now I remember some more! 

elephant in the room

definition: an obvious problem or risk that no one wants to discuss. 

Conversation: 

Sally was playing with her mom's phone. She dropped the phone and the phone broke.  Bob saw Sally hide the phone under a rock. 

At the dinner table, the mom said, "I can't find my phone today'. Bob knew Sally was ignoring the elephant in the room. 

Also, on the movie Zootopia, 

there was a funny joke. the Police Chief Bongo in the meeting said, 'Let's acknowledge the elephant in the room..............Happy birthday (I forgot the elephant's name) There was a real elephant in the room, but he used the idiom and we thought there was a problem. So funny. 

Bite the bullet

definition: to decide to do something difficult or unpleasant. 

Conversation: Bob aks, "Sally, you are going to buy that car?" "I want to buy that car. But I have to get a second job to afford it. I will bite the bullet and do it." 

I hope you understand these! Let me know if you have questions.