Okay, so "Lambda" is a letter in the Greek alphabet. The "mouth" of the stuffed rabbit is actually the symbol of the the upper-case character (Source: Wikipedia). Pretty clever!
Looking up "Lambda Rabbit" brought up science articles that talked about DNA immunoglobulin light chain sequences. Or something. But it appears as though that stuffed animal might be a stealth pun on genetics?
...Yeah, I'm just as confused about this as you guys are.