Stay in your lane

[Becky]

mind your own business; keep moving straight ahead and dont veer over into my personal affairs

[Mark Zuckerberg]

Stop talking about things you dont understand or know. Let experts do the talking. Dont talk out of your ass.
Used in technical forums and websites to indicate a user has strayed into an area in which they clearly have no expertise.
Anecdotal evidence is not passable as expertise, so keep it to yourself unless you have something useful to add.

[Britney]

1. what you say to someone who is below your league in terms of attractiveness and tries to hit on you.

2. what you say to someone who tries to talk about a sector they are not an expert in