Yes you can. From first hand experience -- yes, you can.
Once a tree is established (two years or so), you can pee all you want around the drip line and they usually show nothing but gratitude for your contribution, but even there -- I've got a young mango tree that I've been attempting to help out that is showing signs of burnt leaf ends. Salt damage? Too much N? Both?
For annuals, particularly small ones, you've got to use some moderation. If you are out there in the garden (at night, under cover of darkness), keep the hose moving, so to speak. Don't empty the whole tank on one or two plants, and certainly try to direct the "application" a few inches away from the stem. Tomatoes are nitrogen pigs, but even with young tomatoes, it's easy to burn them. For brassicas, young herbs, and even grains (corn, etc.), I'll usually pee in a bucket that's half-filled with rainwater and will use that more sparingly.
But by the heart of the growing season when the tomatoes are 6 feet tall and the corn and okra are over my head, let it rip.
Citrus trees take it full-strength. You just can't seem to give them too much nitrogen. Stone fruit -- I'll give them a dose once a month or so, but they seem more than capable of finding enough N in the soil.
And I've never once burned the compost pile by peeing too often or too long.
I wish there were some way to calculate how much N has been kept in the system down through the years by faithfully taking a leak in the orchard. My guess, at this point, is hundreds of pounds of N, with significantly less K and P, although measurable none-the-less. If the NKP of human urine (as it's been reported) is 11-1-2, there are hundreds of dollars worth of free fertility being added to the garden annually.
I'd say this: if there is any doubt whether or not human urine is too hot, then just pee on the compost pile and the carbon in the pile will capture a significant % of the N in the stream. You can integrate that N-rich compost into your potting mix, planting holes, or as a soil amendment or top-dressing/mulch.