Imagine saying this to an English teacher:
"I passed my last English test without any preparation at all. I don't think I'll bother making any effort next time either."
Your English teacher might reply:
"Don't push your luck!"
Here is a definition of "push your luck" from Cambridge:
Can you make up your own sentence which uses the expression "push your luck"? Although it's very common in the imperative form ("Don't push your luck"), you can also say things like:
"I think you're starting to push your luck".
Nice idea, Michael.
Here's another example:
Teenager: Mum, can I stay out still 10 o'clock tonight? My friends are all going out to the cinema.
Mother: OK, just this once.
Teenager: Thanks. Oh...and actually, there's going to be a party afterwards. So..um.. is it OK if I come home around, say, midnight?
Mother: Don't push your luck! 10 o'clock and not a minute later. Remember you've got school tomorrow.