The letter X is made to vex. What did children's alphabet literature do before x-rays and xylophones were going concerns? Xanthippe was apparently a popular choice:



Or:

X is a letter that seldom is used,
But its shape will remind us how sinners abused
Their Saviour and God, when, with brute, cruel force,
They compelled Him to bleed and die on the cross!

And, an entire alphabet mocking the Cubists.

Via Languagehat.