To play with fire is to take an unwise risk: to do something dangerous, or something where there is the possibility of loss or failure.
You will often hear people say "If you play with fire, you will get burnt". This means: if you take a foolish risk, something bad will happen to you.
Examples of use:
1. If you argue with Mr O'Dowd you are playing with fire; he's a very powerful and influential man.
2.The government is playing with fire with their changes to the health service.
3. You are playing with fire going on a date with him. He is unreliable and can't be trusted.
Can you write a sentence with this expression?
Does someone you know play with fire?
Image © Pete Coleman