Exactly, pure oxygen coming into contact with any kind of grease and BANG
It's not a great marriage, but takes more than 'contact'.
A CAPTAIN attended a meeting with a burnt face and without his usual well groomed waxed moustache. "What happened?" he was asked. "We lost cabin pressure", the captain explained, "so I grabbed the oxygen mask, slammed it to my face and—whoosh! my moustache caught fire"
True story, apparently, although quite a few years ago (not too many captains with waxed moustaches around any more!).
Also an incident where, I think, a military Hercules pilot's cheese sandwich caught fire as he was eating it. 100% O2 needs a great deal of respect.