You just have to laugh sometimes.....
Some of my recent favourites are:
"I had a terrible night last night. I had to stay awake .. until I went to sleep" (said several times over, with greater emphasis each time, because of course if you repeat it, then it must make sense.)
"drinking water causes gas, so no water, and no salt, cause salt makes you drink water"
"the toothpaste took all the enamel off my teeth in just 3 days!"