relax
Explanation
The Joke
A figure wearing a hockey mask (reminiscent of Jason Voorhees from the "Friday the 13th" horror franchise) stands holding a large machete. Behind him, two people are tied up. The masked figure says: "Relax. Statistically, the odds of being murdered by a serial killer are less than one in ten million."
The joke is that the serial killer himself is using a statistical argument to calm his victims. The statistic about serial killer murders being rare is technically accurate for the general population, but it is hilariously irrelevant to the people who are already captured and tied up by a serial killer. Their individual probability of being murdered by a serial killer is effectively 100% at this point.
The Humor
This comic plays on the common misapplication of population-level statistics to individual situations. People often cite broad statistical odds to dismiss specific fears, but statistics describe aggregate probabilities across large populations -- they say nothing about your personal situation once certain conditions have already been met. The absurdity of a serial killer using this argument on his own captives is the extreme version of this logical error. It also satirizes the way people use statistics as a rhetorical cudgel to dismiss legitimate concerns, ignoring that context matters enormously when interpreting data.