I was at a party and met this woman with young identical twin girls. I said something to her about them being twins and she said they were actually part of triplets. I looked around for another girl and she pointed to a boy.
As you know, you can't have identical triplets/twins or anything if they're different genders, so I apologized for thinking the girls were identical.... even as I'm staring at them thinking, "These kids look EXACTLY alike!"
"They are identical," she said and as I tried to figure out the brother triplet, she explained:
She became pregnant with a set of fraternal twins: a girl and a boy.
The girl split into identical twins, giving her triplets with a pair of identical twins in the 'set'.
Nature is really amazing!