What IS this sound?

[Phoenix]

Driving me bonkers. Sounds so familiar but I can't place it. Three days I think, now, and nobody has guessed right yet.

So, this guy is hiding cash and giving it away, and he has branched out to social media as a way of giving money away. On twitter he is @IHidTheCash ( https://twitter.com/IHidTheCash )


Clues for this sound so far are:

1. Can be found in a gym
2. Can be carried in a car
3. Closest guess yet is of a plastic water bottle being squeezed

You can win his cash if you guess right. He's in the DC / Baltimore area but online anyone can win.

 

[CowboyStar88]

Water bottle would've been my guest

 

[RonSpringsdaman20]

Driving me bonkers. Sounds so familiar but I can't place it. Three days I think, now, and nobody has guessed right yet.

So, this guy is hiding cash and giving it away, and he has branched out to social media as a way of giving money away. On twitter he is @IHidTheCash ( https://twitter.com/IHidTheCash )


Clues for this sound so far are:

1. Can be found in a gym
2. Can be carried in a car
3. Closest guess yet is of a plastic water bottle being squeezed

You can win his cash if you guess right. He's in the DC / Baltimore area but online anyone can win.

I'm not telling you! Go collect my doe!

 

[Phoenix]

Indeed, it was a water bottle. But one like none I've never seen before.

http://i46.***BLOCKED***/albums/f131/vsmith23/waterbottle_zpsbe7cb877.jpg