Push your luck
Definition 1 of 1
Pro Tip 1/3Idiomatic Caution
Suggests overconfidence could lead to problems. Often used as a warning. 
You've won a few games, but don't push your luck.
Pro Tip 2/3Colloquial Warning
Common in casual conversation; gives a friendly alert not to take more risks. 
You got away with coming late once, don't push your luck.
Pro Tip 3/3Metaphorical Edge
Imagines luck as a physical boundary that shouldn't be overstepped. 
She already agreed to one favor, if you ask for another, you're pushing your luck.