Green’s Dictionary of Slang

string (along) v.

1. in senses of persuasion [the image of dragging someone along on the end of a string].

(a) [early 19C+] to fool, to deceive someone, esp. over a drawn-out period of time; to tease; thus stringing n.

(b) [late 19C+] (Aus./N.Z./US) to encourage, to egg on.

2. in senses of movement.

(a) [mid-19C] (US) to progress, to walk along.

(b) [20C+] to accompany.

In phrases

string (along) with (v.) [1910s+] (orig. US)

1. to accompany; to associate with.

2. to agree with.

3. to support.

string on (v.)

[late 19C+] (Aus./N.Z.) to deceive; in a relationship, to lead someone on; to encourage with deceitful intent.

string (someone) out (v.) [1960s+]

1. to keep someone in suspense.

2. to deceive someone over a period of time.