@Pika
Hobgoblin - Majo to Futari -
Finding about a Tsubana manga I somehow didn't know existed is like stumbling across a 5$ note under your couch. I'll also recommend
Dainana Joshikai Houkou, my personal favorite of the author's work. Props also to everyone recommending Douman Seiman, panpanya and Abe Youichi.
Bizzare manga/oneshot concepts that are not The Wandering Dick:
Kiss my Ass - Hemorrhoids-themed romcom. Edutainment at its finest.
Giriri Out - Consistent winner of the best manga synopsis. Stretching the definition of "good" here.
The maiden in love is a carnivore - Oddly enough, this isn't even the only oneshot to run with this concept.
Children can't choose their parents -
...
Weird/Unsettling:
End of Goldfish Kingdom - Not very weird plot-wise, but it's told in a way that always feels a bit off. Maybe it's just me, but either way it's good stuff.
Most of Jiro Matsumoto's stuff is great, but
Becchin to Mandara is definitely his most surreal one.
Paranoia Street - Pretty standard Kago Shintaro fare.
Shiro Ame - A slightly darker Yoshitoshi ABe oneshot. Wish he'd actually decided to continue this one, since it's a cool concept.
Hoshi no Ponko to toufuya Reiko - Absurd degrees of tone whiplash.
Soil - David Lynch movie in manga form.
Saitama Chainsaw Girl - School shooting (Cutting? Sawing?) goes wrong. Also might be stretching the definition of "good" a little here as well.