Oh my! My husband and I chuckled with you. I hope you were able to hold it in while your little guy was telling you it was all okay!!! I have tiled countertops too and the best thing I can suggest is to use a toothpick or shishkabob stick. Sorry, don't have anything better that won't damage the seal on the grout. You have to give him credit though, he did try. But I'm sure he will forever remember you don't clean up flour with water.