spout or sprout
The transition from spout to sprout is an amusing mix-up. The original metaphor goes back to the 1500s, the imagery being words gushing up in an uncontrolled way from the speaker’s mouth. Spouting a message was equivalent to indulging in a rant. The words were uttered without thought, usually because they were of a sloganeering or propagandist nature, or the result of rote learning.
Spout rhymes with sprout, so now the water image has been replaced by the surge of new plant growth. The rod of Jesse bearing a green shoot comes to mind. This seems more benign, and, sure enough, the instances of use all share the notion of the suddenness of the message and the sense that it is a positive one.
There is a basis for this use of sprout in the way it is employed figuratively to describe things which seem to flourish. A bushy moustache could be described as sprouting on the owner’s face. This metaphor for vigorous growth and the temptation of the rhyme has taken us a step too far. At the moment sprouted messages are in the minority but I can see that it is taking hold.