Hackers will often make rhymes or puns in order to convert an ordinary word or phrase into something more interesting. It is considered particularly flavorful if the phrase is bent so as to include some other jargon word; thus the computer hobbyist magazine Dr. Dobb's Journal is almost always referred to among hackers as ‘Dr. Frob's Journal’ or simply ‘Dr. Frob's’. Terms of this kind that have been in fairly wide use include names for newspapers:
Boston Herald → Horrid (or Harried)
Boston Globe → Boston Glob
Houston (or San Francisco) Chronicle → the Crocknicle (or the Comical)
New York Times → New York Slime
Wall Street Journal → Wall Street Urinal
However, terms like these are often made up on the spur of the moment. Standard examples include:
Data General → Dirty Genitals
IBM 360 → IBM Three-Sickly
Government Property — Do Not Duplicate (on keys) → Government Duplicity — Do Not Propagate
for historical reasons → for hysterical raisins
Margaret Jacks Hall (the CS building at Stanford) → Marginal Hacks Hall
Microsoft → Microsloth
Internet Explorer → Internet Exploiter
FrontPage → AffrontPage
VB.NET → VB Nyet
Lotus Notes → Lotus Bloats
Microsoft Outlook → Microsoft Outhouse
Linux → Linsux
FreeBSD → FreeLSD
C# → C Flat
This is not really similar to the Cockney rhyming slang it has been compared to in the past, because Cockney substitutions are opaque whereas hacker punning jargon is intentionally transparent.