A doodle is a small, mindless sketch (although they may represent unconscious thought). People usually make doodles while bored or concentrating on something else, such as talking on the phone or passing time in lectures. The word "doodle" can be used as either a noun or a verb.
Similarly, a doodle can be a short, random musical phrase (also see noodle).
A Google Doodle is the name given to the variations of Google's logo that appear on the website on special occasions.
A doodle is also a colloquialism for a penis in some countries.
In Ralph Bakshi's film Cool World, a Doodle is a a toon or cartoon character.