Mod note: tidied up the off topic post about Witch bottles, which are a different thing from European witchcraft, while this is more akin to hoodoo.
Urine jar spells are usually love spells. (Why, I don’t know, sounds weird to me but ok.)
If you do an internet search and the top results are all about love spells using urine and sugar. A lot of them are from people offering services to do it for you so I can’t link them here per forum rules about promoting 3rd party sites. Some are just clickbait.
Here’s an example, paraphrased with my notes in  … tbh it looks like the "active ingredient is actually the sugar, making this a variant of the Honey Jar spell?
Love Spell with Urine and Sugar
The purpose of sugar is to sweeten the relationship.
- A glass or plastic container (of small size) with a cover [I think a grocery store herb jar would work well)
- Your lover’s photo (small to fit the container)
- Your own urine [Some require your partners urine.]
- Some sugar [maybe a teaspoon].
Put your lover’s photo into the container. With your partner’s photo still inside, fill the container with your urine, making sure it covers your partner’s photo. Set you intention that you have a complete and full love.
Add the sugar and cover it.
Bury the jar. The purpose of burying it is to make sure that the sacrifice is not exposed to sunlight, as this will neutralize the whole effect of the work. [You could also put it at the back of a dark place in the house, like the linen cupboard.]
You know, what’s missing from this spell is the actual working itself! Magick isn’t automatic, you have to do the work to make these things magickal.
So, WHILE you’re doing all that, the most important part is to have your mind fully focused on the loving outcome you want to have as if it was real right now. Imagine all the cool things about being in this relationship as if you already had it, all your emotions, all your dreams and expectations of where it was going. Play your favourite song that reminds you of the dream on repeat if it helps, keep that focus until the jar is put away.
If you bury it, or when you put it away, make sure you walk away without looking back, this shows yourself and the universe you completely trust the spirits that this is going to work and you don’t need to think about it any more.