Scavenger hunts?

I have a question, ladies! I see a lot of announcements where you send your husbands on scavenger hunts to find the positive pregnancy test or announcement that you made. My question is- are they genuinely surprised? We’ve been TTC for a few months, and it would be SO OBVIOUS to my husband what I was doing if I tried to send him on a hunt. Do your husbands seriously not get it immediately, or is it just something fun to do even though they probably have it figured out already?

(Not being rude. I think they are adorable, just confused as to how hubbies don’t figure this out unless the pregnancy is truly a “happy surprise” and not TTC.)