Tiny Tuesday: Mystery Macro

Well here goes.... can you guess what it is??

Was supposed to be in Benbecula as I'm typing, flight cancelled due to bad weather, only after I got as far as Stornoway lol. So I've spent the morning waiting around airports (just for fun). At least I got a bit of studying done on revalidation...

The following is a message from WalkingWombat’s Monday blip.
“I'm really looking forward to tomorrows TinyTuesday6 - Mystery Macrochallenge.  Could I please ask everyone taking part to pass on the message via there journals to other blippers that we should all publish the actual item we publish tomorrow as an extra on Wednesday.  In other words, Wednesday is "REVEAL ALL DAY".   The tag will still be TinyTuesday6 - however a second one TT6MM will help us all to go straight to the mystery macros.  Please pass this on if you can”.

Looking forward to all the answers tomorrow :)