noun
scribbling; doodling; graffiti
Refers to idle or mischievous drawings, scribbles, or graffiti, often done absentmindedly or as a prank.
ノートの端にいたずら書きをしてしまった。
I ended up doodling in the margin of my notebook.
壁にいたずら書きをするのは
Stop scribbling on the wall.
落書き is more commonly used for graffiti or scribbles in public places, while いたずら書き emphasizes the mischievous or playful intent.
Compound of いたずら (mischief, prank) and 書き (writing, drawing). The exact historical derivation is uncertain, but the word transparently means 'mischief writing'.