I’ve got a really good UDP joke...
I’ve got a really good UDP joke to tell you, but I don’t know if you’ll get it
This is another programming joke. It is depends on the user knowing about UDP, and some of the properties of UDP.
UDP is a protocol for sending data across a network. It is fast, but it does not guarantee delivery of the data. "I don't know if you'll get it" can therefore mean "I don't know if the joke will make it to you", or it could also mean "I don't know if you'll understand it" (remember the last joke - "Get" can mean both "receive", or "understand").
This joke therefore boils down to the exact same joke as the last one - a pun that requires domain specific knowledge to understand.