(adj)(v) to speak as if one had a retainer in their mouth which in turn causes all "s" sounds to be pronounced from the back of the mouth with the tongue never touching the front teeth...resulting in a gathering of spit for a modified "sh" sound, possibly showering the recipient of the retainer voice in the speakers spit. often embellished for comical effect by using key terms such as geez louisegosh and shucks.
1. (sh)ally (sh)ure is(h) (sh)uper p(sh)yched (sh)e (sh)ells (sh)ea (sh)ells by the (sh)andy (sh)ea (sh)ore.
2. Do you know what would make that story actually funny, repeat in your retainer voice.
3. Man, I hope he doesnt think any less of me after hearing my retainer voice.