It's an Easter Egg of sorts. Blasto the Jellyfish is a popular action hero in the Mass Effect universe. He's the first Hanar SPECTRE, and was featured in a commercial in Mass Effect 2, which makes extensive use of lines from Dirty Harry:
The origin of Blasto is a joke by one of the ME Writers on the Bioware forums:
Blasto is a reference to a joke made by writer Patrick Weekes on the official Mass Effect forums. When posting in a thread titled 'Your ideal ME2 squad', he included "Blasto the zany multi-pistol-wielding hanar gunslinger with a dark past, a heart of platinum, and the tendency to shout, "Enkindle THIS!" in combat." Blasto quickly became popular among fans, with Weekes noting "I am never going to live that joke down."
In Mass Effect 3, Blasto returns in Blasto 6: Partners in Crime, which, if you interact with the billboard repeatedly, you'll be able to hear about 10 minutes of dialog from. Dialog which is suspiciously similar to Lethal Weapon.
Other dialog around the Citadel will inform you that Blasto 6 has broken box office records (set by Blasto 5, natch), and that it is a very hotly anticipated release.
For my money though, I'd rather see Elcor Hamlet