だの

Stupid things like/Crap like
Plain form word + だの + Plain form word + だの

だの is a negative nuanced version of や.
The Japanese meaning would be something like “などのくだらないこと”
The things listed by だの are unimportant and possibly annoying to the speaker.
だの needs to be used twice in a sentence.

だの is most commonly used to report what someone else said; typically some BS excuse they had.

Because だの implies that, to the speaker, those things are unimportant, it is not typically used with things that ARE important.
So if you said: “仕事だので忙しい”, It implies that work is unimportant/stupid considering the context.

Examples

• 彼はいつもゲームだのアニメだので部屋にこもって仕事もしない
  He’s always holed up in his room doing pointless things like games or anime and doesn’t work.
  
  
• 好きだの嫌いだのとわがままばかり言う (Weblio)
  Always saying stupid selfish things like “I like it” or “I hate it”. 
  
  
• つらいだの大変だのと言われても、門外漢の私にはわからない (Tokyo Foreign Language University)
  You can say its hard or difficult or whatever, but as a layman I don’t understand.
  
  

Extra

According to the Tokyo foreign language university, だの can express the following sentiments:

• Something has no value; I.E. worthless (Most common)
• Something doesn’t seem real (Abstract crap like…) 
• Things that are both (I.E. meaningless and useless, or (uselessly) saying something that won’t happen). 

You may read the relatively short paper for a lot more examples.