Problematic sentence.

[bud-bar]

Hello, I've been watching Whitechapel recently and two guys were talking about a pretty woman. They both liked her and one asks the other why he doesn't do anything to ask her out or something. The other one responded that you shouldn't shag persons whose ranks are higher than yours and then there are following sentences:

(First guy): How would you know?
(2nd): There might have been DCI (lower rank) back in the days.

...and he starts to laugh. My question is, what does the last response mean? That some time ago there was a lower rank than his?

I know what 'back in the days' mean but it still doesn't help me...

 

[SlickVic9000]

(Not a Teacher)

I can't tell you much just from what you've written. You'll have to upload a video of it to youtube or something and link it in your post.