[Crooked Constituent]

I remember the punch line being: you can only fit one dirtbag on a hoover!

[Amish with an attitude]

This joke apparently has a number of punch lines.

"the dirt bag is on the outside"

is the one I'm familar with.

[Salamander]

The punchline is actually "On a Hoover, the dirtbag is on the inside."