Color Inside The Lines
(intransitive) To behave conventionally, to follow the rules.
Example: Used other than as an idiom: see color,â€Ž inside,â€Ž lines.
2008, Craig Detweiler, A Purple State of Mind, ISBN 0736924604, page 55:
Too many don'ts had crimped their creativity and blocked out the wealth of dos. I admire the high standards embraced by my Christian students, but my heart also aches for those who have been raised to simply color inside the lines.
2006, Jane Johnson, Every Kick Ain't Down II, ISBN 1424302242, page 171:
You see, she had already learned to color inside the lines, that is, be as quiet as she could and try to become invisible to simply blend into the wall until it was safe to come out.
2009, Susan Meissner, White Picket Fences: A Novel, ISBN 0307458334, page 107:
They told us to stay on the trail, but of course Bart never liked to color inside the lines.