Why are sausages called bangers?

Conversation over dinner last night...

Liem: (Singing to the Wiggles' Hot Potatoes) Mashed potatoes, mashed potatoes... Mummy, can we have mashed potatoes? Mashed potatoes are yummy.
Mummy: Okay, how about we have bangers and mash next week.
L: Mash are mashed potatoes and bangers are sausages. Why are sausages called bangers? Sausages don't go bang...
M: Errr...(thinking of a very adult and quite rude reason why sausages could be called bangers)...I don't know...
L: I think it's because they wobble in the pan. When Daddy cooks them, they wobble in the pan.
M: (Grasping at any straw to escape the conversation) Errr....you might be right...

Mummy you made me sad

Liem: Mummy, you made me sad...
Mummy: Oh? Why?
L: You didn't get me vanilla yogurt (crying piteously)...

In my defence, there was only 1 pack of vanilla yogurt left and it was past the use-by date, so I didn't buy it.

How to get a 4 year old to say Gong Xi Fa Cai

A few days before Chinese New Year...
Mummy: Let's practise saying Gong Xi Fa Cai. Liem, say Gong Xi Fa Cai.
Liem: I can't.
M: Say Gong.
L: Gong.
M: Say Xi.
L: Xi.
M: Fa.
L: Fa.
M: Cai.
L: Cai.
M: There! You did it. Now say Gong Xi Fa Cai.
L: I can only say Gong.
M: If you practise you can say it. Come on, Gong Xi Fa Cai.
L: Gong.
Mummy retires in defeat.

Along comes Daddy...
Daddy: Hey Liem! Do you remember what to say? Is it Gong Xi Fa Mai?
Liem: No, Cai!
D: Is it Gong Xi Ba Cai?
L: No! Fa! Gong Xi Fa Cai!
D: Ohhhh.....and do you do this? (Waves hand in a circle over head)
L: No! You do this! (Puts hand over fist, does cheng cheng).
Mummy shakes head in disbelief.

From not wanting to say Gong Xi Fa Cai, Liem WON'T STOP saying Gong Xi Fa Cai. On a Skype call with Ah Kong and Ah Por, Liem says Gong Xi Fa Cai continuously.
Ah Kong: Did you go to Aunty Siu Chyn and Uncle Willie's house?
Liem: Gong Xi Fa Cai.
Ah Por: What did you have for lunch?
L: Gong Xi Fa Cai.
Ah Por: Wah, I'm sure to have lots of good fortune this year.
L: Gong Xi Fa Cai. Gong Xi Fa Cai.

Gong Xi Fa Cai everyone!!!