Segg- hard, as skin is.
Cumberland - a wound with a callous skin over it, said to be segg'd(Kennett M.S.)
The Kennett reference dates the term to between earlier than 1728, Kenett's death.
Dictionary of Archaic and Proverbial Words J O Halliwell, 1847
A regular saying of my mothers was;
"if you sit round much longer doing nothing you'll get segs on your arse".
Jim Carroll