Clump noise when braking suddenly

My 2004 Odyssey (with less than 2K miles) makes a clump noise when I stop suddenly. A friend of mine who owns a 2002 Odyssey said that she has the same problem, and the dealer told her that it was the gas swishing around in the tank. This make a little sense because it really does sound like liquid swishing....and I only seem to get the noise when I have over a half of a tank of gas. Does anyone else get this clump noise when stopping suddenly and/or can you provide any explanation?

there is a check valve ball in the tank and thats what makes the noise. its not the frluid its the check ball thumping.

So is this normal to hear it clunking around? Or is there something that I can do to stop the noise? Thank you for the info!

if thats the noise then yes its normal and there isnt anything you can do. There is another clicking noise that happens when you change directions and apply the brakes. like doing a three point turn or backing out of a parking spot. this is from the brake pads shifting thats a normal noise to. assuming that either of these two noises are present.