Don't believe him stirring up gossip behind people's backs.
Tips
usage
Two distinct registers: (1) physical fiddling - playing with hair, prodding objects, plucking strings (拨弄琴弦 'pluck strings'); (2) figurative manipulation - 拨弄是非 ('stir up gossip / sow discord') is a very common collocation, always negative. Context disambiguates.
memory
拨 (poke / stir) + 弄 (mess with) - both characters carry the sense of touching something to change its state. Together they emphasize repeated, fiddling motion or meddling.