The phrase "think outside the box" needs to go.
1.) If you're encouraging non-traditional thinking, shouldn't you be using a different metaphor? "Think outside the box" is a tired clause; if a supervisor uses this, you're probably dealing with someone who has a terminal lack of imagination and probably doesn't practice what they're preaching.
2.) I've found that the phrase is often thrown out by supervisors who have no clue what they're doing themselves and are simply using it as a way to delegate tasks downward while attempting to bolster their own image of superiority. It's a bad excuse. If you want somebody to get a job done and do it well, then teach them how to do it instead of giving them vague guidance and walking off.
3.) I had a boss who used this phrase all the time. Needless to say, it was a bad work environment, and I ended up leaving the career field far behind because of this one asshole. This phrase is now burned in my memory as something that bad supervisors use.