Originally it meant timid, and it was called "Shrimp Climbing", and later it was called "Shrimp". Now the word "shrimp" is generally used in different contexts.

If you use "shrimp" to your friends: it is a fight between ordinary friends, a kiss or you are timid;

If you use "shrimp" to people you don't know: it's pure swearing, saying that you have no courage, no initiative, inferiority and cowardice.