This is definately the best time to tickle someone 🙂
Back in the early 2000's I had a gf for a couple years, i'll call her Cindy. It was a slight distance between us so we couldn't see each other all the time, but me and her best friend used to talk a lot, and it was her best friend that used to tell me to tickle her. Well I told her that when I couldn't be with Cindy to tickle her to cheer her up. True to her word she did, most of which were on the phone.
One of the most memorable was one night, I called her and then throughout the conversation she was giggling, she was staying at her best friends for the night, and her friend was singing. I thought that she was laughing at her friends singing, but then I could tell she was being tickled, just by the way she would just suddenly keep giggling then talking normally again. Then it got to the point where she would really start laughing, and couldn't even speak. From that point I said my usual goodnight love u baby, bla bla, and then just after she spoke back she started giggling again, just before I hung up. I wish I had recorded it it was a cute conversation.