No, not the kind you take around Christmas or the 4th of July. Holidays are those nasty tiny unpainted spots in your painting. They can happen if your paint is too dry, if your gesso has an uneven surface or you are painting carelessly. They can really detract from a painting causing the eye to focus on a very light point in your composition and when the viewer realizes that the area is unpainted, he or she can be left feeling that they are viewing the work of a non-professional.
The solutions are obvious. Up the amount of medium to make the paint to move more freely and always take time to examine your painting carefully before allowing people to view it. Another simple solution is to tone the canvas with a color of your choice. This means that any holiday will be pink or green or whatever. It can actually add a dimension to your painting and provide a unifying element of color repeat throughout the painting. Naturally, this means that before you start, you must predetermine your color palette so that your toning base will complement the finished painting. Have fun!