Who, me, pull an April Fool on my players?

It didn't work quite as well as I'd hoped, but well enough.

The Swords group are in Pavis in Fire Season, a little split up, but with the current action in the Rubble, at the end of a fight.

9:30 on Friday, I posted this:

As they examine the body, they're aware that it's getting a little cooler, and
not quite as dazzling - a welcome cloud blocking Yelm from view, perhaps? A
breeze starts up - probably Dori playing with the icy North Wind again. She
doesn't usually cause shadows, though... and the first person to look up will
realise that what's blocking Yelm's rays isn't a cloud. Not unless clouds have
huge, slowly-flapping wings, anyway. There's some very big flying creature
approaching from the north-west, and while at the moment the silhouette makes it
look black, the edges of those wings are a reddish colour - crimson?

 

shortly followed by this:

Should have said - this is visible from anywhere in Pavis, so all PCs can
respond. Anyone who was in Whitewall will recognise it. The mega-aura of fear it
projects hasn't quite got here yet.
 

And then, after a long and rather disappointed pause, at 12:00, this:

(sigh) - don't you people read your email on a Friday morning?

It gets closer, it gets more and more obvious that it's Bat-shaped. And then
there's a loud POP!!!!! and it explodes. Little bits of cloth fall out of the
sky - not much, but some. Somewhere to your west - probably a long way to the
west, but loud, and carried by the wind, someone's giggling - but even that is
cut off short, with what might have been an "ouch!".

 

But it had worked, it seems: at 15:23 this came in:

Cruel cruel woman! I read the mail but didn't have time to reply, but you
totally had me.....I never even considered today's date.

Swine!
 

As I then pointed out (after punching the air and yelling "WIN!", to the slight startlement of the rest of the office):

And it really can have happened, in-game. Somewhere over there, there's a
Trickster who's pretty good at illusion magic, and whose boss is now annoyed
with them.