Well, not every time. Sometimes you should use an apostrophe to make a plural. Here’s a note from the Chicago Manual of Style and Daily Writing Tips: DO use the apostrophe to form the plural of an abbreviation that combines upper and lowercase letters or has interior periods: The department graduated five M.A.’s and two Ph.D.’s this year. NOTE: If you leave out the periods, you can write MAs but you’d still have to write PhD’s. DO use the apostrophe to form the plural of lowercase letters:
I didn't do this - but I TOTALLY would!!! I tore a sign down off the front door at work the other day. When my boss asked me what I was doing, I told her I was fixing it because customers were going to think we were stupid before they even walked in the door.