You don't Pee on your Plants lol. That does nothing but risk burning them just like when a Dog Pees on the lawn and it turns the green grass in to a brown patch. If anything you could take a dump in the Plants Soil and mix it in well then water. All Manure works great in Soil. Soft mushy Mashed Potato Dumps and straight up Diarrhea would be best for it to be absorbed. If it's a Hard Rock Turd then you should get a Steak Knife and slice and dice it up before adding to Soil so you can get it distributed more evenly throughout. But yeah try to avoid peeing on them. 
