Before you send me to the helmet thread, I want you to know, I've been there. Yes, it is helpful and I will be looking into the replies.
However, my current helmet (Giro Bevel) is not very tight around my head. If I hit the ground fairly hard, or rock my head side to side it slips off.
When I ski I wear a hat along with my goggle strap underneath my helmet. I understand that these are probably the reason for my 'loose helmet symptoms' but, a lot of people wear their gear like this, as well as the pros, who throw massive tricks with huge flips and spins, I've never seen their helmets get loose. I wanted to see if others face the same problems. If you have recommendations of any kind, I would be very appreciative.