I go to put my 1 year old to bed. And she always wants to give her brother who's 10 a hug and kiss…

I go to put my 1 year old to bed. And she always wants to give her brother who's 10 a hug and kiss but lately she makes a kissing noise saying muck meaning Mateo (my son's name) and she leans in the slaps him so tonight I hold down her hand and she head butts him and starts laughing. Luckily he has a fast reaction and moves out of the way. She thinks it's hilarious lol..... Don't know how to make her stop though