The name Java is not an acronym. In particular, it does not stand for Just Another Vague Acronym. The language was originally called Oak, but the language lawyers worried about the name Oak Technology (at the time a maker of video cards). So a meeting was held (varying accounts of that meeting were gathered up by JavaWorld), and the name Java made the short list. The language lawyers approved, and the rest is history.
Most kinds of executable file formats have some kind of "magic number" that identifies them. For example, old PDP-11 executables for the UNIX system used the "magic number" 0407 (the real magic there, and the putative origin of the term, is that 0407 was a machine instruction for a jump forward of 7 words, i.e., past the 8-word-long executable header, to the first executable statement in the program). Some versions of the Berkeley UNIX memory allocator use the hexadecimal string 0xDEADBEEF, which is considered unlikely to occur in normal operation(!), to uniquely identify a section of memory that has been allocated to the user. Not to be outdone, the Java Virtual Machine uses the string of hexadecimal numbers 0xCAFEBABE to identify valid JVM files, a kind of homage to the origin of the Java concept. Just who is, or was, this "cafe babe"? You'd have to ask James Gosling!
Finally, it's been pointed out that the Java magic number also forms the "smiley" "]~:>"when viewed in ASCII.
0000000 J ~ : > nul etx nul - soh 4 bs soh ! bs soh - cafebabe 0003002d 01b40801 a10801ad 0000020
One final word: the "cafebabe" magic number had also been used years earlier at the Mach project (Mach was almost forgotten until Apple chose to incorporate it into Mac OS X) to indicate their executable file format:
$ grep cafebabe /etc/magic 0 belong 0xcafebabe compiled Java class data,... 0 belong 0xcafebabe Mach-O fat file