The phrase "ask for trouble" suggests that someone is behaving recklessly or foolishly and is inviting negative consequences upon themselves. Synonyms for this expression include "court disaster," "tempt fate," "invite trouble," "challenge fate," "beg for trouble," "tempt trouble," "provoke danger," and "set oneself up for problems." These phrases all convey a similar sense of someone acting in a way that is likely to lead to negative outcomes. Using these synonyms can add variety to your writing and help convey a sense of danger or risk to your readers.