Table: yugoslav_football_results_5
Columns: date
city
opponent
results
type_of_game

Question: What day was a friendly game held that had a score of 2:3?
SQL: SELECT "date" FROM yugoslav_football_results_5 WHERE "type_of_game" = 'friendly' AND "results" = '2:3'

Question: What type of game was held on December 22?
SQL: SELECT "type_of_game" FROM yugoslav_football_results_5 WHERE "date" = 'december 22'