While once a standard way of expressing amusement online, the usage of XD has long since been confined to the less intelligent among us. Can also be used ironically (oftentimes in all lowercase, as "xd") and/or as an adjective.
You, livestreaming Super Mario 64: *falls off the edge of the world*
Retard in chat: XDXDXDXDXDXDXDXDXD
You: Shit, how'd I fall off? That was kinda xd...
Retard in Discord: helo wats ap . i wan 2 kno, how do get girlfren ?
Normal person: xd
Retard in chat: XDXDXDXDXDXDXDXDXD
You: Shit, how'd I fall off? That was kinda xd...
Retard in Discord: helo wats ap . i wan 2 kno, how do get girlfren ?
Normal person: xd
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