OK, this one's pretty weird: a Japanese "toy" that Flickr user Greg Jagiello found at the Daiso store in Daly City, California. The swan got a little packet of stuff that once you squeeze it, a chemical reaction occurs and the "thing" inflates fully...
Translation of text on the box:
Fuooo-!! (action word of the swan popping out after holding the wing)
The swan's head pops out!!
With the "erect" swan, be the king of the party?!
How to operate:
After placing the swan on the pants, pull down with your hand on the head (grasping), then let go -
Muku Muku - Boing!
Make mostly of Nylon
For people 12 and older.