Sometimes when speaking you may blank out a bit, forget a little word or phrase, and you need something to say while gathering your thoughts. Or maybe you need to stall for a while. Well, the word "那个"（nèige) is just what you need.

Basic patterns:
In English, words like "uhm" and "er" are used as filler words when you're thinking about what to say. In Chinese, "那个"(nèige) is used for this purpose. This can sound a bit unfortunate to English speakers, but it's very common in Mandarin and you'll hear it quite often around Chinese speakers.

"那个" can be inserted into sentences wherever you need to pause for thought. This is similar to the slang use of "like" in English, or filler words in general.

Examples:

Nàɡè, wǒ bú hé nǐmen yìqǐ chīfàn le, hǎo mɑ?
那个，我 不 和 你们 一起 吃饭 了，好 吗？
So. . .uhm, I won't eat with you guys, OK?

Zhè ɡè píjiǔ yóudiǎn nàɡè. . . nàɡè. . .
这 个 啤酒 有点 那个... 那个...
This beer is a bit. . .uhh. . .well. . .