throws in

Verb

throw in (third-person singular simple present throws in, present participle throwing in, simple past threw in, past participle thrown in)

1. Used other than figuratively or idiomatically: see throw, in.
2. (informal, transitive) To add something extra free of charge.
   • If you take the large size, we'll throw in a set of tea towels.
3. (informal, transitive) To include in a calculation.
   • Throw in Mr Trump's promise of a "great, great wall along our southern border" - with estimates starting at $12bn - and "massive tax relief for the middle class", and the price tag for his speech proposals is on an express elevator to astronomical.2017 March 1, Anthony Zurcher, “Trump addresses Congress: A kinder, gentler president”, in BBC News
4. (idiomatic) To quit, to fold.
5. (archaic, transitive) To inject, as a fluid.