Blockhead Signlang

A language that makes use of the only practical mode of communication between blockheads and everyone else, Blockhead Signlang is a collaboration between merfolk and blockheads devised in the year 16 APB which vastly empowered blockheads of many different walks.
At its core, it allowed blockheads and any species with human-like hands to converse without hiring a pheromone interpreter, meaning that not only did interactions with the Redspawn and other blockhead organizations become much smoother and more meaningful, but now blockhead individuals who couldn't afford to have an interpreter on-hand, especially for casual conversation, had the power to just communicate with anyone.
BHSL was especially empowering to blockhead sires and, to lesser extent, blockhead hermaphrodites and ex-sires, as though sires are utterly excluded from communicating in pheromones and hermaphrodites/ex-sires are not adapted well to voicing their needs, any member of the species with hands can talk in BHSL. This proved definitively that the imbalanced inability/difficulty to converse does not correlate with lesser intelligence.
Lastly, it's a better platform for storytelling. Though blockheads can convey theoreticals in their pheromones, the systems in place simply do not allow one to fabricate a person out of wholecloth. With blockhead pheromones, names are inherent, which mandates that anyone with a name be real. As it turns out, though pheromones can't convey nonexistent persons, the blockhead mind can still comprehend such a thing.
BHSL requires that merfolk ignore the extra knuckles and fingers blockheads have and that blockheads adapt their signage to mitigate confusion.

Geographical Distribution

Pretty much restricted to Anicoja.

Common Phrases

Index finger held up, palm facing viewer

"Hello" or "Hold up"

Hand & fingers flat, waving back and forth parallel to ground

"Goodbye" or "Go away"

Middle finger extended up, palm facing viewer

"You infuriate me"

Finger gun pressed into front of head

"This is an unpleasant experience"

Finger gun pressed into side of head, then jerked upwards

"Kill her" or "Kill them"

Index & middle fingers pressed into other hand's palm, then jerked upwards, followed by thrust-forward chin

"Where can I get something to eat?"