Here you see the results of a successful #seagullbuttstickshaking session, as it is performed by a professional. NB. Hardly any seagulls were harmed in the making of this photograph.
One last thing I wanted to mention about this: The first few times you do this, try to make sure there is no one around. They might think you are totally crazy until you get the knack just right, when they will see you mean business and stand in awe.