In the Royal Navy they were known as "Spitkids",were made of aluminium,and were polished up for Messdeck Rounds.Of course, nobody ever gobbed in them,well,not in the 1960s,anyway,but a friend & fellow folkie of mine ( a Scouse mandolin- player called Ned S------)was reduced in rank for coming back to his messdeck rat-arsed one night,and having a crap in one (for which they were not designed).History does not record how,or indeed with what,he wiped,if indeed he did,the offending sphincter.The Captain giveth,and The Captain taketh away.....