I’ve never O-ed in a poem. Then again, I’ve never Oh-ed, either.
Oddly, I’ve just noticed the old O last night, in my Poetry Northwest, which includes a Yeats and a Blake and their O’s. And here you are with a question on new O’s.
oOs are calling me.
I prefer Dale’s shape of the mouth idea.
[Poetry Northwest also published an engaging poem that includes a few symbols, including a smiley and equal signs, in “Notes on Compression” by Campbell McGrath.]