What Does "gaegosaeng" (개고생) Mean in Korean?

This is a crude, informal term used primarily among friends, colleagues, or peers to vent about shared struggles. Because it contains '개-' (dog), which is a common prefix for vulgar intensification, it should be avoided around superiors or in formal settings, where you would use '고생' instead. It conveys a deep sense of shared exhaustion or 'victim-bonding' after enduring a frustrating task together.