Why, with one of those things in your hands, you could become an instant expert, reading the latest happenings in the world of DC Comics while catching up on the history of your favourite - and not so favourite - heroes.
My in-depth research tells me I had thirteen in total - and those thirteen are pictured above and to the left of these very words.
Sadly, thanks to my disgraceful policy of never paying more than 99p for a comic, I fear I may never again lay my hands on most of them, which always insist on selling for more than that sum on eBay. Still, despite my Scroogeilicious tendencies, I do have the 100 page Witching Hour and the yellow-fronted 100 page DC Super Spectacular starring Superman. I also possess Superman Family #164.
From what I can remember of the others, the highlights included a Neal Adams Batman tale featuring the caped crusader versus a werewolf, and the Jim Aparo Batman of Detective Comics #438.
The Justice League 100 pager gave us the tale of the murder of Santa Claus. Although my memories of the other strips in that issue are somewhat slim, I seem to recall one of them featuring the Justice Society tackling a gang of juvenile delinquents, a task which logic would suggest they were more than a little over-powered for.
The Superboy one, I have fond memories of. I seem to recall it reprinted the origin of the Teen Titans. Did that issue also feature the story where Supergirl got her head chomped on by a lion while she was dressed like she was Sheena, queen of the jungle? For some reason that image has always stuck in my mind.
Superman #272 was an all-magic issue, which was fine by me though Superman at one point had Saturn Girl's pet, Proteus, stuck to his face, which can't have been a pleasant experience for him. The Flash hundred pager featured a group of sidekicks modelled on the Three Stooges - or perhaps they were the Three Stooges. My memories of it are as fuzzy as the end of Marilyn Monroe's lollipop.
But, all in all, it was the Batman/Detective Comics issues that made the most impact on me. Through them I got to see the work of Neal Adams, Jim Aparo and Dick Giordano, learned of Batman's origin and got my first sightings of Man-Bat and Manhunter. So, thirteen might be unlucky for some but for those of us who had them, it proved to be more than lucky. The moment you saw the number thirteen in this post, you knew I was going to end this post by saying that, didn't you? Mr Predictable? Me?