My work has a Halloween costume contest that is a force of nature. There's big prize money on the line: $100 for the best costume, and $75 and $50 for runners up. I took this seriously and all, but I'm also super cheap, so here's what I came up with:
You should know that I work in IT, so this is way more funny than it seems. It was easy and funny, and most people knew what I was. It involved acquiring a white cocktail dress, white foam core and tissue paper. The dress was $16 on Amazon and I'll wear it again, the rest came from the dollar store.
I cut the poster board into a cloud shape, then pasted on a package of white tissue paper. I pasted on logos of different cloud computing programs, then snagged some photos from my desk to add to my cloud.
I didn't win, but I also didn't put a lot of time or money into this, so oh well.