A phrase used to describe people who are boring/low self confidence/wear glasses/have no mates/study geology.
A stringy melt wouldn't stick up for themselves or their friends in any situation and is generally not a good person to have around.
A stringy melt will always wimp out of fun things.
'Those geology boys are such stringy melts'
Bob - 'Jim you fancy coming out tonight?'
Jim - 'Nah got ballet lessons'
Bob - 'You stringy melt'