Use an ink pen or similar item to punch about 10 holes in both sides of a brown paper lunch bag. Sit the unripe tomatoes into the bag with the stem ends facing up toward the opening of the bag.
Put a ripe apple into the bag along with the tomatoes. The apple helps speed up ripening by releasing ethylene gas.
Fold the end of the bag down so it's secured shut. Set the bag of tomatoes on the counter top.
Open the bag and inspect the tomatoes after 24 hours. If they are ripened to your likeness, take them out. If not, put them back in the bag, seal it shut and leave them for another day.
Check the tomatoes every day until they are ripe. It can take from one to five days for them to completely ripen depending on their ripeness when you put them into the bag.