'throw in' definitions:

Definition of 'throw in'

From: WordNet
verb
Add as an extra or as a gratuity
verb
Give up in the face of defeat of lacking hope; admit defeat; "In the second round, the challenger gave up" [syn: drop out, give up, fall by the wayside, drop by the wayside, throw in, throw in the towel, quit, chuck up the sponge] [ant: enter, participate]
verb
To insert between other elements; "She interjected clever remarks" [syn: interject, come in, interpose, put in, throw in, inject]

Synonyms of 'throw in'

From: Moby Thesaurus