really not sure what makes a cartoon funny, but the most successful
ones tend to be those that imply an action rather than show it. In
this case the central character is the bird "Polly". If
I had drawn part of the bird sticking out the end of the vacuum cleaner,
showing the process of what was happening, it wouldn't have worked.
The text helped enormously as well, even though it mentions nothing
of what is going on. Polly's owner is worried about the noise... if
she had said "Take polly out of the cage or she'll get sucked
up the vacuum cleaner", it would have been a pretty sad cartoon.