POC||GTFO issue 2 (from 2013) was a PDF and a bootable OS at the same time:

From section 8:

"A careful reader may have noticed that a bootable OS image was hidden in the last issue of PoC k GTFO, as one of the files in its dual PDF/ZIP structure (if you haven’t, download and extract it now!). This time, though, let’s hide it in plain sight. You will find by running ‘qemu-system-i386 -fda pocorgtfo02.pdf’ that the PDF file you are reading is also a bootable disk image."

https://greatscottgadgets.com/pocorgtfo/pocorgtfo02.pdf

And issue 3:

"This file, pocorgtfo03.pdf, complies with the PDF, JPEG, and ZIP file formats. When encrypted with AES in CBC mode with an IV of 5B F0 15 E2 04 8C E3 D3 8C 3A 97 E7 8B 79 5B C1 and a key of “Manul Laphroaig!”, it becomes a valid PNG file. Treated as single-channel raw audio, 16-bit signed little-endian integer, at a sample rate of 22,050 Hz, it contains a 2400 baud AFSK transmission."