First and foremost, yes that is “Chunk” from the Goonies… moving on…
A chunked putt is incredibly frustrating and ultimately costs your strokes. It happens to all of us from time to time, and the root cause is nearly always the same. And that is a drop in spine angle.
Spine angle can change in a number of ways to cause the chunk, but most often its from your head dropping towards the ball slightly, or you changing the level of bend in your body when you’re over the ball during your backswing.
Remember, a change of less than a half of an inch can cause the chunk, considering you address the ball with the club starting on the ground in the first place.
To help combat this there’s a couple things you can remember, but the best one, and the simplest is to keep your chin off your chest. The simple act of keeping you chin up will help you keep it more stationary during your stroke. Sometime good putters can get complacent and slowly their posture starts to deteriorate. This usually starts with the either the head, or the body slouching over the ball, which makes moving around during your stroke much easier.
Another common fault that can change your posture during your swing is eye movement. In general its best to focus on a single spot behind the ball during your stroke. If you’re eyes begin to move around, or look to early, it becomes very easy for your posture to change than can easily result in a chunk or other miss-hit.
So before every putt, stay tall, keep your chin up, and keep your eyes steady for your stroke. These simple tips will help you eliminate chunking from your game.