Per 
The flash drive that contains SCP-5XXX
Item #: SCP-5XXX
Object Class: Safe
Special Containment Procedures: SCP-5XXX is contained on a 4 gigabyte USB drive, currently located in site [REACTED], where it is guarded and locked in a 3'x3'x8' storage closet.
Description: SCP-5XXX is an MP4 file that when played, plays a McDonalds Filet-o-Fish commercial that first aired in February 2009, which lasts 43 seconds. If listened to once, it has no anomalous effects, but they begin to manifest once listened to for prolonged periods of time.
Testing: Testing on Class-D personnel has returned the following results:
The first symptoms manifest at around 5 loops of the commercial, where the subject begins to sing along with the commercial. After around 10 loops, The subject appears to be singing it passively, with either little to no awareness that they are listening or singing along to the commercial at all. After 20 loops, The effect becomes so great that the subject is unable to stop singing along to the commercial, and must be forcibly removed from the audio range of SCP-5XXX in order to hold a conversation or respond to questions. after approximately 25-30 loops, the subject will continue to sing the song for anywhere from 1 to 20 minutes even after SCP-5XXX has been stopped. At 351 loops, the subject becomes unable to stop singing, and will continue to sing, only responding to questions or talking with others when threatened by force. At 40 loops, the subject will begin drawing and hallucinating various objects. These have been noted to be a singing wall mounted fish, as seen in the commercial, a Filet-o-Fish itself, or sometimes the McDonalds logo. After 50 loops, the subject becomes unable to speak any words besides the short jingle from the commercial. Even when tortured/threatened, the subject will continue to speak these words until they are physically unable to speak at all. At 60 loops, The users Cognitive Functions begin to rapidly decay, and will continue to do so until effectively rendered in a vegetative state, only able to preform basic bodily functions, and utter the jingle from the commercial. The subject also does not respond to ay stimuli. At 70 loops, the subjects body alters in a way that physically prevents their digestive system from digesting any food except for water and a McDonalds Filet-o-Fish sandwich. Replicating the sandwich in a different fashion, or at a place other than a McDonalds franchise, also results in the digestive system rejecting the food via Vomiting. At 80 loops, the subjects body tissue alters and takes a composition similar to the meat-substance found in a McDonalds Filet-o-Fish. This should result in total organ failure, but the subject continues to remain alive until other factors result in their death. Once 100 loops have been reached, the subject begins to develop a covering that resembles that of bread crumbs on a Filet-o-Fish sandwich. This takes around 24 hours to occur, but the bread-crumb shell is impenetrable, rendering the subject invulnerable, presumably until the subject dies of natural causes.
Addendum: We will be testing its effects on various other SCPs shortly
