get off my lawn

This expression has been used to characterise the relationship between Trump and the Black Lives Matter protesters, particularly since they had the temerity to invade the White House lawn.  It is the response of an ageing WASP to anything that is new and different, particularly when coming from the younger generation.

The image behind it is that of the suburban white male glaring at children who had dared to cross his perfectly manicured lawn.  In the case of Trump this seemed very apt. It is used ironically in response to some pronouncement by an  older person to point out that they are demonstrating curmudgeonly conservatism.