I saw somewhere that the actor improved that line which means he blurted it out with Riker standing right there which feels totally in line with the tone of the episode they were shooting. It's funny to me on so many levels.
Definitely watch the Ready Room episode. They talk about a lot of this. I remember another interview where Tawnie Newsom, I think, talks about how Frakes, Quaid, and her just kinda took over the set because they were all nerding out, being silly, and improv-ing a bunch because that’s what they do on LDS.