Absolutely. It would be done by inserting one boys finger into the others anus (Butt hole). This would be considered fingering.
If the person's ring finger is longer than the index finger, it's a boy. If the index finger is longer the ring finger, it's a girl. Hope this helped!
u get ur middle finger (because its the longest) and where the hole is that the penis goes into the vagina, place ur finger there then push into her and out The question was " how SHOULD a boy finger a girl " and NOT how a boy SHOULDN'T finger a girl, that is how you don't do it, unless you don't want her to let you do it again.
A pointer finger :p
It feels good, idid it before It feels good when I finger myself, it feels good when another girl fingers me, and sometimes it feels nice when a boy fingers me, but they all feel different, I wanted to know what it really feels like for a girl when she has her hand up inside another girls knickers and has her finger going up inside her.
Only if they have a drop of a man's (or boy's) semen on their finger.
15cm is quite large for a small finger (if by that you mean pinkie finger), even for an adult.
Yes, of course a boy can finger you when you're on your period. Menstruation doesn't stop you from doing anything that you'd do any other time of your menstrual cycle.
No; it feels good.
This may sound horrible, but my friend told me that it is when a boy/girl sticks their finger up someones.... arse.... >.< I know, grose. But that's what she said.