['Mix 50/50 toothpaste and baking soda, rub in. ... ', 'Rub in a paste of salt and olive oil, allow to sit for up to an hour. ... ', 'Rub in Miracle Whip (Mayonnaise) and wipe off after an hour.', 'Mix 50/50 vinegar and olive oil and rub into the watermark.', 'Try straight toothpaste (non-gel).']