A gas turbine engine exhaust mixer has a plurality of circumferentially distributed alternating inner and outer lobes. The outer lobes protrude into the annular bypass passage of the engine, whereas the inner lobes protrude into the main gas path passage of the engine. The inner and outer lobes respectively define alternating troughs and crest with radial interconnecting walls therebetween. The mixer has a jagged trailing edge including a plurality of tabs extending from each radial wall between the troughs and the crests.