This looked close-enough to a pepper plant that I let it be this spring, but I have absolutely no clue what it is now that it's fruiting:
Nope. No spikes whatsoever. It looked exactly like the plant does now, just smaller, and no fruit or flowers. The leaves, early on, weren't serrated (or whatever you would call the spikes coming off their edges) like they are now. That plant you linked is near my garden, though. The stem reminds me a lot of a pepper plant, too, but more "fleshy" you can see it in the top left corner the 2nd picture.
steve The plant in that photo is Horse Nettles (Solanum carolinese) aka Caroline Horsenettle which is not a true nettle. It is poisonous because of a toxic alkaloid Solanine that it produces. Best to look at other photos online to help you make a positive identification. HTH