Someone is telling you a storyyou don't have time for. You also don't have the time or patience the say "Get to the fucking point," or may be in public, so you elect to say gttfp.
GTTFFJ is an acronym that means get-taehyung-to-fall-for-jungkook.
Basically, it is an acronym used by taekook-shipping ARMY with no lives who read amd write fan fiction and low-key stalk seven, admitidly hot korean men.