Just because millions of people share the same mental idea, should we not find it as hysterical as the lone whacko in the tinfoil hat who leaves jellybeans out for Shub-Niggurath? That's what interests me - that our culture leads us to think that "praying" is such a natural and normal and logical thing to do that we DON'T just laugh and laugh and laugh when a grown adult tells us that's what they are going to do.
Throughout human history, deity worship has been common and the norm as opposed to an oddity. Because that has been the case, prayer has never been considered funny or ridiculous. Those things that an untainted and culturally objective observer would find stupid, weird, or funny are not generally funny to the sane masses because the practice of things like prayer, speaking to a deceased love one at their grave site, and singing praises to an unprovable god are the norm and widely accepted as such.
Therefore laughing at someone praying is like laughing at a man for pisssing while standing up, it's kind of silly and weird.
I don't think the analogy holds, though I see what you're aiming for. Urinating while standing is - I don't think - a cultural thing, but rather a biological thing: we tend to be upright (or at least we are upright at the point where we arrive
at the place we intend to squirt) so there is no "need" to change position.
A better analogy would be with ettiquette, and the way to lay out and use knives and forks at a formal dinner. Forks have prongs, knives have blades, and I seriously doubt there is anything that you cannot do with this
fork that you can
do with that
one. It's something done for a non-functional reason because of the "belief" that it is right to do so. Frankly, I'd find it amusing to be told "no, not that
knife - that
knife" at dinner - but fortunately such practices seem to be falling into disuse.
Prayer and god-belief though perhaps falls better into the camp of superstition and the OCD-end of mental illness, maybe. As such, perhaps instead of the "laugh" reaction being appropriate when someone says "I will draw for you/I will stroke a black cat/I will switch the light off and on 32 times", it would be better to express sympathy and - perhaps - direct them to a counsellor.
But to draw it back.....yes, prayer to an invisible being (who can do anything but normally chooses not to) IS considered "normal" in our culture, because of the hundreds of years of precedent.
But why the heck should that continue to be the case? For what reason should one offer any different response to the man who says "I will pray" than to the man who says "I will sacrifice a goat"?