'Snails \'Snails\, interj. God's nails, or His nails, that is, the nails with which the Savior was fastened to the cross; -- an ancient form of oath, corresponding to 'Od's bodikins (dim. of body, i.e., God's dear body). --Beau. & Fl.

Source: Webster's Revised Unabridged Dictionary (1913)