I'm usually round I'm as light as a feather Thousands of men cannot carry me What am i?

Why this works

This riddle plays on the contrasting properties of bubbles. The phrase "I'm usually round" refers to the typical shape of bubbles, which are spherical. "I'm as light as a feather" highlights how bubbles are filled with air and are incredibly light. Lastly, the line "Thousands of men cannot carry me" emphasizes that, despite their lightness, bubbles are so delicate and ephemeral that no amount of strength can physically grasp or transport them without causing them to pop. This clever combination of descriptions makes the answer, bubbles, both fitting and fun!