Explain SMBC — the wiki for Saturday Morning Breakfast Cereal

This comic plays on the concept of anonymous charitable donation. A man wearing a mask (to remain anonymous) approaches a woman while holding a jar labeled "SPERM," saying "Don't think of me as a hero." The caption reads "Anonymous donation is not always the highest form of charity."

The joke works on multiple levels. There is a well-known saying that anonymous giving is the highest form of charity, since the donor seeks no recognition. The comic subverts this by applying the concept of anonymity to sperm donation, where a man wearing a burglar-style mask delivers his "donation" in person. The humor comes from the absurd collision of the noble principle of anonymous charity with the decidedly less noble act of hand-delivering a jar of sperm while wearing a mask, as if this were some heroic deed deserving of praise.