It was only a matter of time, really. The unofficial tag line of The League now has its very own collection. The options for meta-expressing your (and your infants'!) ennui, etc. are plentiful.
And if you haven't visited the League Store recently, why not explore for a bit? I've made a number of improvements and additions over the past few months. The Zazzle folks have also completely overhauled the entire site and it's, like, super hipster now. Which means some baffling design choices, but a generally smoother interface.
As always, please let me know if you're hankering after something that isn't yet available, and I'll see what I can do! (Though I can tell you right now that Zazzle does not stock clothing for cats. *sigh*)