If there is any definition of "ironic", it must be a smiley face seen in a cancerous cell:
Australian researchers at the Westmead Millennium Institute for Medical Research were investigating how the protein beta-catenin invades a cell's nucleus and causes it to become cancerous, when they spotted the protein apparently mocking them. You can see this a bit more clearly in the video they made:
The circle is the cell's nucleus as the protein moves in, and the dark spots are where the protein is blocked. The smiley face doesn't surprise me; we're hardwired to see faces and familiar shapes everywhere we look (click the tag marked "pareidolia" -- the psych term for this -- under this post to see lots of examples). Heck, I spotted one in a supernova once...
And I certainly hope this research yields insight into how to fight cancer. I'd love to see that smirk wiped off that nucleus's face.
Tip o' the gamma knife to Amos Zeeberg and Fark. Image credit: Westmead Millennium Institute for Medical Research