混(hùn) - to mix, to muddle; to drift along in Mandarin

混 (hùn) starts from the physical idea of things flowing together and mixing, as in 混在一起, mixed up together, and it stays useful there: 混合 to blend, 混乱 chaos, 混淆 to conflate two things that should stay apart.

Its second life is the interesting one. Colloquially 混 means to get by without effort or ambition, to scrape a living, to hang about somewhere. 混日子 is coasting through your days, 他在北京混了几年 is he knocked about in Beijing for a few years, and 混得不错 is doing rather well for yourself, said with a shrug. There is a third sense of slipping in where you do not belong, as in 混进去.

The trap is the drifting sense sounding neutral to an English ear. 混 in that use is faintly disparaging, so telling someone 你在混 is a criticism, not a description. Note also that the character has a second reading hún meaning muddy or muddled, which is what you hear in 混蛋, and that reading is an insult.