I use the impostor-pieces to build a statue showing MichaelD.965's cleansing of GOG, chasing the anti-forum-gamers and notorious downvoters away, gloriously.

I suppose that means you leave the anti-forum-gamers and downvoters to me...wonderful! I send them to my arena and have them fight to the death for my amusement...they wanted to take away our fun, now they pay for it! The worst offenders have to fight against my komodo dragons with pen knives...hahahahaha!

I leave my mini-Colosseum to the next user.

[I fill the Colosseum with lions and leave it to the next to post.}

Since the Colosseum is tiny, I chose to believe it's the giant Lego model, which is micro-scale. I have nowhere to put something so big, so I take it apart for spares and 1 of the Lego lions goes with my One Piece figures as apart of Buggy's crew.

I leave the next user a 1-size-fits-all black sweater with rainbow stripes and plunging neckline.

Wonderful, exactly what I didn't need.
I build a scarecrow, dress it with the sweater and a straw hat, and put a sickle in its hand.
I slowly back and start running, because I swear that thing started to move.
The sweater must be cursed or something.

I leave the scarecrow to be investigated by the next user. Please exercise caution!

Do autopsy and find amazing discovery.

Leave something that was smuggled inside of the scarecrow

It's a disgustingly vile, beating and pulsating demon heart radiating pure evil...apparently it had possessed the scarecrow.

I leave it to the next user, since I've never had much interest in the supernatural.

I feed the demon heart to my neighbor's (not really) starving dog and she demolishes his house; One Punch Man was casually walking by and swats her into oblivion.

In the smoking rubble, I find whatever the newest Xbox is called in perfect working order and leave it for the next user.

I save the new XBOX until it has more games for it, and play my older systems for now.

For the next person I leave a ticket to Phantom of the GOG-pera..the hit new musical gracing the forums. :D

I'm not gonna watch a dude wearing a mask, incoherently babbling and whining while playing the organ!

I sabotage the show and leave the organ to the next person.
(I keep the mask and the cloak and vanish singing into the night.)

I carry off the organ from a small local church and replace it with the newer, better one with a much better sound (taken from above). After the successful organ transplant I leave a generous donation of toys for next Christmas' needy children.

I leave a Star Wars Millennium Falcon Lego set for the next person.

Put up the organ to be from the 1900s that was actually from today up for sale and make a $150,000 profit. Buy multiple musical instruments for a grand total of $143,897.

Leave the 50,000 musical instruments and change of $6,103 to the next user

I take the 50.000 organize a program for helping kids with limited income that wish to learn music. I leave the next user the satisfaction of watching them learn.

I assist in instructing the youths who become some of the greatest minds in Advanced Astrophysics, many go on to work at NASA and in the aerospace industry and are respected authorities in the fields of Physics, Astrophysics, and Jet Propulsion Engineering. Several of them have been awarded the Nobel Peace Prize and are now not only famous, but wealthier than ninety nine percent of other beings residing on Terra.

I leave an extensive volume on Advanced Astrophysics written by the brightest of them for the next user. Merely holding the textbook in your hands and opening it to any page will increase your IQ by twenty points or more.