Eat? Oh god, hopefully no. Some people do cut them up to miniscule pieces and chew them so that the fentanyl gets absorbed buccally through your mouth. It's VERY dangerous practice though because it's very hard to get the dosage right and a lot of people have outright died from OD this way.
Thomas and colleagues published a case report of a 42-year-old male with known drug abuse, including hospitalization for drug overdose, who died subsequent to oral ingestion of fentanyl patches [6]. Upon autopsy, the decedent had three pieces of fentanyl patches in his stomach. Further history reveals that the decedent commonly chewed, sucked on, and swallowed fentanyl patches to obtain a high. Lastly, Woodall and colleagues reported a case series of seven deceased patients in whom oral administration of a fentanyl patch was suspected to have contributed to their death [7].
More recently, Carson and colleagues presented a case of a 28-year-old white male who died in the ED after chewing and aspirating a transdermal fentanyl patch. On autopsy, the decedent had a beige foreign body (later identified as the transdermal device) lodged in the mainstem bronchus, and postmortem toxicological analysis revealed a serum fentanyl level of 8.6 ng/mL [8]
Fentanyl is 50–65% bioavailable across the buccal membrane when administered as a transbuccal system (e.g., lozenge and troche) [1, 9, 10]. However, when ingested orally, fentanyl undergoes extensive first-pass metabolism, resulting in 20% escaping hepatic metabolism and entering the systemic circulation. Therefore, as alluded to in published case reports, the time fentanyl stays in contact with the oral mucosa directly translates to the systemic absorption and the severity of the overdose.