The Invisible Spray is a blue bottle that is pretty small in height. The product has its name written in red within a yellow background on the can, similar to the Exploding Chewing Gum. There is also a "warning" box with a red background at the bottom.
SpongeBob and Patrick use the Invisible Spray to prank the people of Bikini Bottom, by making themselves invisible and pretending to be ghosts. Towards the end of the episode, Mr. Krabs throws water at SpongeBob and Patrick to make them visible again in a bathroom stall at the Krusty Krab, where they were revealed to be naked, due to the spray staining clothes. Once SpongeBob and Patrick walk out of the bathroom after apologizing to Mr. Krabs for threatening to burn a dollar, the latter shines a spotlight on them and the audience humiliates them for being nude in public. This results in the two regretting buying the spray in the first place and agreeing that they should have bought the whoopie cusion instead.
When Frank holds the Invisible Spray bottle, the bottom of the bottle had a "Danger" sign on it. However, in every other shot of the Invisible Spray, the label is missing. This may be because the "Danger" part is a separate sticker and was ripped off by SpongeBob and Patrick.
The Invisible Spray stains clothes which is the reason why Spongebob and Patrick were revealed to be naked after Mr. Krabs splashed water on them.