Thumbs-down grip on a cross

I was invited to a confirmation ceremony this weekend. The Swedish church holds confirmation events for eight-graders and it's one of those deeply ingrained cultural things that young kids do just because. It usually consists of a mass in church, a hearing and then a family party where the kid gets a load of expensive presents.

I noticed a weird thing that I wondered about: The procession was led by one of the kids holding a cross in a weird way, cross-gripped with his thumbs down. It didn't seem like a natural way of holding a cross, or anything for that matter. Couldn't find anything about it online as google just pointed me to gun-sites for some reason. Anyone know why this particular way of holding a cross is used?