You're getting beside yourself

My Grandma was Southern born and raised, so a lot of Southern Dialect , sayings and nuances were little lessons throughout my life. One of those sayings that I favored is " You're getting besides yourself"- My grandma would say this to me anytime she felt I was trying to "show off", "Act up" or get "too cutesy". It was a soft way of saying, "get back in line", or "get yourself together", "humbly thyself". It is usually used by someone elder or maternal/paternal, is helpful and surely is an expression of love!