It happens 5 hours ago. I was picked up by some friends of my friends to take me home. We were 4 in the back and since the car is too small the sister of my friend sat on my lap. She is gorgeous, and she was wearing a tank-top so I could see her beautiful and smooth armpit. Well in the road I saw that the sister of my friends always put on hand above her head to grab the roof to not get hit in the head, I always checked her armpit wishing so bad to tickle it, well in one of those, the temptation won me and I tickle her there, she laughed a lot and put her hand down, in that moment everyone look at her and i said "so you are ticklish?, what should we do about that?", "I know" one of my friend beside me said, I pushed her where the other were, and the sister of the girl grabbed her arms above her head while my friend and me tickle her in the armpits and sides, She started laughing a lot and try to kick us, but couldn't everyone were laughing as we tickle her. We couldn't tickle her more because I got home, so she was safe. Well that's all. Hope you like it