throw in is a verb meaning "add as an extra or as a gratuity". It carries 3 recorded senses.
add as an extra or as a gratuity
give up in the face of defeat of lacking hope; admit defeat
“In the second round, the challenger gave up”
Definitions, synonyms and semantic relations for throw in come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.