If you're looking for sympathy you'll find it between shit and syphilis in the dictionary.

The line is a deliberately abrasive way of saying that sympathy is not something one should expect as a default response—especially in hard-nosed, unsentimental settings. By locating “sympathy” between two vulgar or unpleasant words, the speaker mocks self-pity and frames the desire for consolation as naïve or indulgent. The humor depends on shock and on the pseudo-authoritative “dictionary” reference, which turns a moral rebuke into a punchline. In effect, it’s a comic injunction to toughen up, stop fishing for emotional validation, and deal with circumstances without expecting others to cushion the blow.