Mine is skimming a recipe in a book too quickly. Several times I've got all the ingredients, got myself ready to cook and then read, 'marinate for 8 hours' or 'add ingredient X'. And then I think "oh goodness me" or words to that effect. Or I suddenly realise that the ingredient I was supposed to scatter or dollop on the meal is still in the fridge or waiting somewhere hours after I've eaten the meal. Also toasting flaked almonds. I don't know how many fricking times I've popped them under the grill, nothing seems to happen so I go off and do something else and suddenly I smell the damn things burning!