What does my girlfriend mean by this?

When I was speaking with my girlfriend earlier, She said when we are kissing she would like me to put my arms "around her waist". We got in to a little more detail and she said on her backside. She doesn't want me to put my hands in her pants or feel around, she just wants me to put them down there and leave them there while we're kissing... I think. Could anyone tell me what she might mean if I have this wrong, and if I'm right, How the heck would I get my hands down there anyway? We're both the same height.