In terms of the official brainrot dictionary, " skibidi " is used in may ways, but the most precise and accurate defining of this word is, " skibidi is an intensifier " as said skibidi toilet.
eg. skibidi toilet. looking at " skibidi " as an intensifier, we can see that this basically means" very toilet " so thats why skibidi toilets have heads: to show how very much of a toilet it is.