The spray stuff really doesn't provide enough protection but I am told that no-one in the changing rooms would dream of owning roll-on deodorant.
He isn't usually phased by what other people think, but this does explain why he always remembers to take a spray deodorant but mysteriously forgets the roll on. However, it's not really working. Is roll on really that uncool - or does anyone have a fashion aware teen who would use it? Would shaving his armpits perhaps so that the spray on is more effective be acceptable to a cool teen? (And yes, I know I should be encouraging him to think for himself - I do and he usually does - but this one is clearly a step too far.)