A parent who is also a volunteer coach for youth athletics. Taken from the combination of Dad and Coach, but the meaning has become applicable to any parent coach combination.
The art of being dreadfully shitty and awesome at the same time. This state of being can be obtained only by spending extended periods of time with other doaches of the same gender. This adjective can be used in place of awesome, good, superb, etc.
Doach #1: "What's up, brah? You get any head last night from your girl?". Doach #2: "Yeah, man, it was fucking doachtastic!"