Why do I feel like I need to pee during anal

So I took my new glass anal dildo into the shower in the attempt of finally having a prostate orgasm, but instead I had a feeling like when you've held in going to the toilet for ages. It was sort of nice, but I'd already gone to the toilet before showering, so I'm a bit confused as to what I was doing :/ was it prostate stimulation?

Yep you're right it can give you the pee type feeling but just keep doing it you may find after a while clear "stuff" running out just go with the flow, be careful with glass if you have a ceramic shower tray or have a rubber mat.