asatte no houkou
the direction to the day after tomorrow
to a completely wrong/unexpected direction; far off the point; off the mark/base
It metaphorically indicates in an ironic/sarcastic tone that something goes in a completely wrong and unpredictable direction. For instance, an uncoordinated person often throws a ball towards 明後日の方向 (an unpredictable direction).
It is also used to indicate that something/someone goes far off the point, e.g. “明後日の方向に組織改革をした” (They did their organisational reform in 明後日の方向), meaning “Their organisational reform was far off the mark”.
Difference between 予想の斜め上を行く and 明後日の方向
予想の斜め上を行く is used for something both positive and negative and emphasises that something is unique, bizarre and/or unexpected. On the other hand, 明後日の方向 usually indicates that something is unreasonable and off the mark. Another difference is that 予想の斜め上を行く sounds much more slang and is predominantly used on the web.
I kicked the ball and it flew far away from the right/intended direction.
The discussion is going off the point/in the wrong direction.