Have something down pat
verb phrase
To know something or be able to do something perfectly; be perfect master of something: I had my story down pat, so I almost believed it myself ( first form 1896+, second 1915+)
Read Also:
- Have something going for someone  verb phrase To enjoy a certain advantage; have particular assets: You’ve got more going for you with NTS home training/ The best thing this mall has going for it is it’s just a test (1960s+) 
- Have something going with someone  verb phrase To be amorously tied to someone (1970s+) 
- Have something made  Related Terms have something cinched 
- Have something on  see under have nothing on 
- Have something on someone  verb phrase To know incriminating information about someone: now I have something on her (1919+) 
