What is a poke, head and handy?

I know this is a weird question but all my uni friends talk about it and I don't know what they mean:$! It often happens at parties and people say these things and need to pretend I know what they are talking about. So what does it mean when a boy pokes a girl? And when a girl gives a boy head? And when a girl gives a boy a handy? Please help me :(!