An ahoge アホ毛 is something that we commonly see being incorporated into the character design of most anime series. Literally translated as “foolish hair” it is commonly used as a visual cue (a single lock of hair sticking on top of the head) to identify characters who have a more naive or carefree personality.
One of my favorite anime character whom I thought had a very interesting ahoge was Koyomi Araragi from the anime Bakemonogatari. If is able to form a question mark when he is confused ^^
It is however important to note that an ahoge is different from Shokkaku (触角), which is used to describe the hair on a character’s head that is in the form of a lock of hair resembling one or more antennae. Nonetheless, both ahoge and shokkaku can be considered as an moe element on a kawaii female character.