The Hamster Dance is one of the earliest internet memes ever made in 1998.
The meme consisted of a serious of rows of animated GIF hamsters dancing to a modified version of “Whistle-Stop” song.
The meme quickly became famous as it gathered many views even in actual televised news reports.
The CORE Dev Team adopted this “mascot” to create an old-school windows95 internet authentic aesthetic.
Most of the CORE Hamster art is created by a NFT artist that has the Pixel Hammies Collection which is a collection well received by the Core community.
This is mostly the reason that you see a lot of PFP of hamsters in the forum and chats. And if you want to keep the Hammie tradition you don’t need an NFT to change your PFP into a hamster 
References:
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Hampster Dance - Wikipedia - info
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The Hampster Dance - a modern hamster dance page
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The Hampster Dance website in 1999 in Netscape Navigator 4.04 - YouTube – how it actually looked like
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https://opensea.io/collection/pixel-hammies - hammie collection
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https://rarible.com/token/0x60f80121c31a0d46b5279700f9df786054aa5ee5:35721?tab=overview - direct link to mona lisa NFT