Title text: Bruce Schneier believes safewords are fundamentally insecure and recommends that you ask your partner to stop via public key signature.
Safe words are designated words for sexual play which are meant to be called if one partner is uncomfortable with the way things are proceeding. Calling the pre-chosen "safe word" would be a sign to stop. To prevent accidental usage, people generally pick words that they wouldn't normally use. In the case of this comic, the characters are chemists, and the uncommon word they happen to have chosen is Ribulose-bisphosphate carboxylase oxygenase, also known as RuBisCO (which actually isn't a very uncommon word, as it's the most abundant protein on earth, but it would be uncommon to use the full word). However, the length of the word makes it impractical for a safe word, as it would take too long to say.
In the image text, Bruce Schneier is a computer security professional, and public keys are the publicly known half of public-key cryptography, which uses two mathematically linked keys to decrypt information.
- [Person in background (out-of-frame) screams out this word over all 3 panels.]
- Sub: RIBULOSEBISPH..
- Sub: ...OSPHATECARBOXYL...
- Sub: ...ASEOXYGENASE!
- Dom: Oh, Sorry!
- Megan: Man, chemists pick the worst safewords.