Most browsers accept SVG as a favicon. So Emoji can slip into favicon space as an SVG <text> element. post 
`<svg viewBox="0 0 100 100"> <text y=".9em" font-size="90">🎯</text> </svg>`
http://js.ward.asia.wiki.org/assets/pages/snippet-template/basicjs.html?snippet-template HEIGHT 400
Serve this as content-type: image/svg+xml.
<link rel="icon" href="data:image/svg+xml,<svg xmlns=%22http://www.w3.org/2000/svg%22 viewBox=%220 0 100 100%22><text y=%22.9em%22 font-size=%2290%22>🎯</text></svg>">
See also Grapheme Cluster Awareness
.
More crazy unicode symbols useful for favicons or other exotic applications. See Twitter Pixel Art Editor
Squares and circles. 🟦 🟩 🟨 🟧 🟥 🟪 🟫 ⬜ 🔵 🟢 🟡 🟠🔴 🟣 🟤 ⚪