Blood Suckers are the Pens that Suck Blood
At some point when I was in elementary school, a classmate of mine came in with a very fancy pencil case. His father has been on a business trip to Japan and picked it up over there. It had all these fancy buttons, hidden compartments, and switches. We were all extremely jealous and things got competitive.
Since none of could score a similar pencil case, a lot of effort went into scoring unusual pencils and pens. They were an object that was useful for school, and therefore would not be confiscated, but allowed us to express ourselves.
In 1983, Blood Suckers showed up in the classroom and swept through like a tidal wave. They were gross, weird, and creepy, which made them the perfect pen for kids trying to outdo each other in the 1980s.
They had two designs, with two colors for each design. The designs were a mosquito and a vampire bat (I had the bat). The idea of the pen was simple. Each pen had red liquid in a clear plastic shell, and when you held the pen pointing up, it would fill with blood. Then, as you wrote, the blood would drain away. The illusion is similar to the one they use for toy baby bottles, where it looks like the baby is drinking.
This of course meant that it took forever to write with it. Since you never wanted to be writing while the pen was not doing something interesting blood-wise. This meant taking frequent breaks, which teachers didn’t like much.
Because of this, these did not go over well in my school. Also, I think the teachers were a bit freaked out by a pen that gave the illusion of drinking/sucking human blood.
Here is a classic commercial that illustrates just how cool the Blood Sucker pen was.