slap togetherSee: THROW TOGETHER(1).
To make in a hurry and without care.
Bill and Bob threw together a cabin out of old lumber. The party was planned suddenly, and Mary threw together a meal out of leftovers. 2. To put in with other people by chance.
The group of strangers was thrown together when the storm trapped them on the highway. Bill and Tom became friends when they were thrown together in the same cabin at camp. [TahlilGaran] English Idioms Dictionary ▲