Never 'snapped' a cue per say but damaged one.
Wife and I had a disagreement so I left the house (detached garage with my games room above) and went to play pool. I was shooting and she walked in and started at me with bullshit and I snapped. Scariest moment of my 30yrs alive I'd say, I blew up at her like I've never heard myself and remember in slow motion looking at the floor while my hand gripped my Carolina Custom about midway up the shaft, I then proceeded to try to put the butt of the cue through the floor. Nevertheless the floor won that one and the buttcap shattered. It was a surreal experience for me; I remember being super calm immediately afterwards, picking up the pieces, walking out and packing my bag and leaving.
Haven't looked at the cue since that day as it's sitting in the closet in a case with a ziplock bag holding the few peices I found on the floor.