don't let down 

Although "Don't let down (me)" sounds like the opposite to "Don't leave hanging(me)" the two phrases are synonymous Both phrases are about support or more precisely about losing needed support. If you ask another not to let you down you're asking that person not to take away their support. On the other hand if you ask a person not to leave you hanging, again you are asking them not to take away their support and leave you "hanging"

I need your help, please don't let down (me). I'm depending on your help, don't leave hanging (me).

don't let down by orbsphere June 6, 2018

don't let the mofos get you down 

A contemporary version of the old expression, "don't let the bastards get you down," this version stands for "don't let the motherfuckers get you down." The mofos are generally anyone in authority or authority figures, whether bosses, family members, partners etc.

"I hate my job. The boss asked to clean the bathroom."
"He's a jerk. Don't let the mofos get you down."

don't let the mofos get you down by kingharvest November 5, 2009