I've been a fairly regular wearer of ear plugs and normally use the orange or yellow foam cylinders. I've never had an issue with them coming out, etc. But I did drink the koolaid one year at the IMS show and had customer plugs made and they were a problem.
Once I put on my helmet, yawned, smiled or pretty much anything that involved facial muscles, the "seal" would break and I'd have all the noise back like an on/off switch from hell. Distracting, annoying and in to the garbage they went.
My foam plugs have never done that over the past dozen or so years I've used them.
Possibly the material they used? My first pair were of a quite firm material and did not fit as well as my newer ones which are much softer. The newer ones stay in a lot better and are a lot more comfortable to wear for extended periods.
'08 Vee: Suzy luggage, Crash bars, Rad Guard & front mudguard extension, Zumo 550, Oxford Hot grips, Stebel, PC-8, 12v acc, Scott oiler & lube-tube, Remus Revolution Cans, Bark Busters, Phillips Extreme vision +100 bulbs.
'08 Concours 14: Rad guard, Stebel, Oxford Hot grips, Projekt D Screen, Hugger, GPS mount, helmet locks & front guard extension, Zumo 550, Stebel, Phil's rack & Givi V46, Sheepskin seat cover, Phillips Extreme vision +100 bulbs.