The reference is to sporting situations in which a goal is left unattended or a court open.
Person 2: Kind of like your mum.
Person 1: Screw you!
Person 2: Sorry dude, you left yourself wide open for that one.
2) Looks like a tornado came through here! Yeah, the kids were wide open at the birthday party.
3) What do you mean I didn't get much done today? Fool, I was wide open. I attended two meetings today and still finished all of names’ and my paperwork back up off me I handled my end.
Note: use with the phrase "out of control" for extra emphasis.
Call for back up this party is wide open out of control!!