dowsing
Explanation
This comic plays on the pseudoscience of dowsing rods -- the folk practice of using forked sticks or rods to supposedly locate underground water, minerals, or other hidden substances.
In the first panel, a person says they have a "skeptic of dowsing rods" but watched a guy use them "and they work." They demonstrate the rods crossing, saying "See?" In the second panel, a skeptic explains that dowsing rods work through the ideomotor effect -- unconscious muscle movements -- noting that "saying dowsing rods work because the rods move is like saying a metal detector 'works' because it beeps." The key point is that the rods moving is not evidence they detect anything; the question is whether they accurately locate what they claim to find.
In the third panel, the dowsing believer deflects entirely, saying "Not fair! Is your magical skeptic brain available for parties?" In the final panel, the skeptic admits the "conversation would work very quickly" at parties -- a dry joke about how debunking pseudoscience tends to kill social interactions.
The comic illustrates a common pattern in pseudoscience discourse: confusing the mechanism of an instrument with evidence of its efficacy. The rods do physically move, but that movement is caused by the user's own hands, not by detecting underground water. It also touches on the social awkwardness of being the person who explains why popular beliefs are wrong.