1.
If you ~ a remark when having a conversation, you add it in a casual or unexpected way.
Occasionally Farling threw in a question.
= toss in
PHRASAL VERB: V P n (not pron), also V n P
2.
If a person who is selling something throws in something extra, they give you the extra thing and only ask you to pay for the first thing.
Pay ?4.80 for larger prints and they ~ a free photo album...
They were offering me a weekend break in Paris–with free beer thrown in.
= include
PHRASAL VERB: V P n (not pron), V-ed P, also V n P