Chock Full

In my never ending quest to understand idioms, I present another bothersome one: chock full. Where the hell does that come from? Although the OED explains that it is uncertain, though this is its best guess:

The uncertainty begins with the first appearance of the word as chokke-fulle, cheke-fulle in the alliterative Morte Arthur, the spelling of which is very insecure. Conjectural derivations are from CHOKE v. (ME. choke, cheke) with sense ‘full to choking’, or ‘choked full’; from CHEEK (ME. cheke, CHOKE n.2) or the related chokes = chops, fauces, with sense ‘full to the chops’; from ME. CHOK, chokke ? to thrust, ram in, in sense ‘crammed full’. Either of the two former derivations would give an original long {omac} (which might perhaps, however, be shortened in the combination); the third would give short {obreve} from the beginning. Prob. there is a recent association with CHOCK n. and v., in some of their senses, but the latter are too late to be the origin; it is more likely that these senses have been developed under the influence of chock-full: see CHOCK adv.

God Bless the OED.