Someone who is muscular built but don't want to show his or her muscles in the public. Hence the expression "Ripped in the reed" - The person rather go in the reed to swim instead of exposing his or her almost naked, well trained body on the beach.
– Where is your friend? I thought he was swimming with us here on the beach?
– No, he is in the reed taking a swim.
– Well, he doesn't want to show his muscular body in front of every one.
– I understand, well thought of him.