Okay, I've gotten a bit of a discrepancy when I've discussed this topic with others before. I know you've heard the phrase, but what does it exactly mean?
On its face, the term "Go Ahead" touchdown seems to imply the defense let the offense score, like... "go ahead and score so we can give the ball back to our offense." But, that's probably not the case.
Or it could mean the offense scored so effortlessly, it was as if the defense intentionally made it easy for them.
I've heard other TV broadcasters use the phrase, but they seem to say it in different situations, so it's hard to pin down the exact meaning.