My bf is taking clindamycin 150 mg. He neds to take it for a week. It says take 1 capsule by mouth 4 times?

It would be best to take every 6 hours. But, that is not always practical. Even in hospitals medications that need to be taken 4 times daily are often not given every 6 hours. Waking a patient every night to take a tablet isn't necessary. Our four times daily (QID) is 8AM, 2PM, 6PM and 10PM.

4 times a day is: 4 doses taken during wakeful hours (when you get up, lunch time, supper time and bedtime) Every 6 hours is just that: the doses are spread apart by 6 hours. ie 6am, 12n, 6pm and 12m. They are close but not the same. This time the guy wins!

4 times a day means at breakfast, at lunch, at dinner and before bed. He doesn't need to interrupt his sleep cycle by taking it every 6 hours

Yes, he is supposed to take it every 6 hours, which is 4 times a day. Tell him the reason it should be every 6 hours and not 4 times a day while he is awake is because the drug gets metabolized (body breaks down the drug within 6 hours) and it needs to stay active in your body for it to be effective at killing the organisms. If he only takes it while he is awake, the drug might wear off while he is sleeping (if greater than 6 hours), and that will give the organisms a chance to multiply since there is no presence of the antibiotic drug to prevent its growth. And tell him to make sure he finishes all of the anitbiotics because if he doesn't, it will not fully eradicate the organism and it will grow even more leading to more infection.