Why don't you say hello to rare steak and rare steak?

The question is a humorous question with a brain teaser. The answer lies in the pun understanding of the word "strange":

Literally: Medium-rare and medium-rare refer to the cooking degree of the steak, that is, only medium-rare and medium-rare are cooked respectively, and there are more raw meat left in the steak than fully cooked. The "undercooked" here means that the steak itself is not fully cooked.

2. Extended meaning: In the context of brain teasers, "unfamiliarity" is skillfully used as a metaphor for "unfamiliarity" in interpersonal relationships. In other words, when two steaks met in the street, they didn't say hello because they were "unfamiliar".