I stole a bottle of water from Starbucks because i thought i had paid for it.

One time i went to starbucks, I was hungover and i ordered a chicken and bacon sandwich and a bottle of water. I wanted to eat it in starbucks and i asked them if that was okay. This was in the UK so you wouldn't normally eat in Starbucks. They said that was fine and then they gave me this little receipt thing to take to the bar. When i got to the till, the guy scanned my sandwich and then he gave me my change. I walked off and sat down at a table to eat my food. A few minutes later this lady comes over and says "excuse me, did you pay for your bottle of water?" And i said "yes." Then she asked to see my receipt and i showed it to her and she said "this is just for your sandwich." I didn't want to look like a thief so i said "oh shit i completely forgot about the water. I thought i had paid for it." I didn't forget about the water. I did it on purpose. But my brain just went into panic mode and i didn't want to get in the shit. She looked at me like i was some sort of idiot. Then she just said "its okay." Like yeah i know its okay bitch. Its just a bottle of water. My brother always laughs at me for this.