Once when I as about 6 and before I knew better I was bobber and worm fishing for sea run cutthroat kelts in the spring. While fishing in a back eddy I have an onl spawned out steelhead come up and push my bobber around with it's nose. it did so for a halh an hour solid before it lost interest, never once did it try to "take " the bobber it just seemed to be literally playing with it.