I/he/she wasn't born yesterday!

something that you say in order to tell someone that a person is not stupid and cannot be easily deceived.

You'd better think of a better excuse about the dent in my car. I wasn't born yesterday, you know!

You can't expect your mother to believe that - she wasn't born yesterday!

• have a lot irons in the fire
• have [a lot of/a few/several etc.] strings to bow
• have [a lot of/a few/several etc.] strings to your bow
• have a lot of strings to bow
• have a lot of strings to your bow
• have a lot of time for
• have a lot of time for someone
• have a lot of time for something
• have a lot on plate
• have a lot on your plate
• have a lot to answer for
• have a memory like an elephant
• have a memory like a sieve
• have a mind like a sieve
• have a mind like a steel trap
• have a mind of its own
• have a minute to call own
• have a minute to call your own
• have a monopoly on
• have a monopoly on something
• have an ace up sleeve
• have an ace up your sleeve
• have an axe to grind
• have an ax to grind
• have an ear for