push your luck idiom (also push it)
愚蠢冒险；得寸进尺
to try too hard to get a particular result and risk losing what you have achieved
She's agreed to help on Saturday, but I think I'd be pushing my luck if I asked her to be here the whole weekend. 她同意周六来帮忙，不过我想我要是让她整个周末都来的话就是得寸进尺了。