Meaning:

“电车” means “tram,” and “男” means “men.” Originating from Japanese, this term (“Densha Otoko,” or “Train Man”) is the title of a Japanese movie, television series, manga, novel and other media, all based on the purportedly true story of a 23-year-old man who intervened when a drunk man started to harass several women on a train. The man ultimately began dating one of the women. Densha Otoko is a popular example of the “nice guy” kind of Japanese geeks who wish to lead normal lives, but are too shy to find a girlfriend. Chinese netizens use the term to generally refer to timid introverted men.

Example:

A: 周末我去看电影，遇见小明和一个女孩也去看电影。

Zhōumò wǒ qù kàn diànyǐng，yùjiàn xiǎomíng hé yīgè nǚhái yě qù kàn diànyǐng。

I ran into Xiao Ming and a girl at the theater when I went to see a movie over the weekend.

B: 真想不到，小明这样的电车男也有勇气约女生看电影。

Zhēn xiǎngbúdào，xiǎomíng zhèyàng de diànchēnán yě yǒu yǒngqì yuē nǚshēng kàn diànyǐng 。

What a surprise! A nerd like Xiao Ming could pluck up his courage to ask a girl out on a movie date.