Note in the proposed passage, Colonel Sanders and Colonel Blimp are not connected except by confusion over a reference to "The Colonel".
I read in a serial fashion. I see 'the Colonel' and then 'Colonel Sanders'. I can see a link between the two. Then I read 'Colonel Blimp', and try to link it to the first two references. 'Colonel Blimp' is meaningless to me, and I don't see how it relates to the first two references. Since the intent of 'Colonel Blimp' is not clear, I have to stop and think about it to determine what, if any, link is present. I may never understand what is meant if I don't know the girl is fat.
That verbal exchange takes me out of the story. That can be a bad thing to do as it irritates some readers.
As EB said:
I wouldn't see that association that way. But then, some of those sort of associations are regional based
Regional associations may need to be explained to the reader. If you have to explain what your character's comment means, you probably shouldn't have your character use the association. Although it can be explained in the context that other characters didn't get the association. Better to use something that almost everyone is familiar with if explaining has a negative effect on the flow of the story.