What is Stfu Mf-er?
pronounced: es-tee-ef-you-em-ef-er. a way of saying: shut the fuck up mother fucker.
used in texting, short hand messages, or even in a stressful situation; if someone insults me I'm like, "STFU MF-ER!"
See shut up, mother trucker, mother fucker, stfu, shut your mouth