Judges do have a sense of humor
You'd be surprised at how many of the opinions I read in my casebooks make me laugh. A lot of judges don't mind sprucing up their opinions with a little humor when the occasion demands. There was, for example, a case about whether a fish bone in a stew made it not meet a warranty of merchantability in which the judge went into great depth about the history of fish stew. Another one that every law student reads, usually a couple of times, starts out, "W thought that we would never see / A suit to compensate a tree."

Here's a one-liner that made me laugh this morning ". . .we doubt that even so eminent a composer as plaintiff Irving Berlin should be permitted to claim a property interest in iambic pentameter." Irving Berlin v. E.C. Publications, Inc., 329 F.2d 541 (2d Cir. 1964)(Berlin sued Mad Magazine, claiming parody was not fair use).