my DD did this for a little while also at that age.
As hard as it is best thing I found was to ignore it completely, no words, no eye contact, absolutely nothing, no reactions what so ever, just put her down and walked away, she soon got the message that if she did it then she wasn't going to get anything in return.
For Abby she really did it for a reaction I think, whether it be positive or negative, they just love to see reactions and facial expressions, ....gee I wonder if I can make her do that again.

I used to also work a lot with autistic children and this method of behaviour therapy worked wonders.

HTH
Laura