[生活美語]
Q: What is “朝聖" in English?

A: The direct translation would be “to make a pilgrimage (n.) 朝聖.”

pilgrimage – http://oald8.oxfordlearnersdictionaries.com/dictionary/pilgrimage

A more colloquial translation for the usage you see on ptt would be “to gather around to see a show.”

That is, when people “朝聖” on ptt, they are basically gathering to see an event unfold (展開).

Since they feel that they must do this, much like how a pilgrim has to make a pilgrimage, they use the term ”朝聖.”

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A related term would be “to leap on the bandwagon,” a phrase that means to support something popular.

jump/leap on the bandwagon
http://idioms.thefreedictionary.com/jump+on+the+bandwagon
http://www.yiym.com/leap-on-the-bandwagon

Sample Sentence:

1. While everyone on ptt is busy “making a pilgrimage” to a specific post and adding needless comments, the world is quickly moving by. Once again, a day of progress is lost.

2. Posters on ptt often leap on the bandwagon and enforce mob justice (暴民的正義) with little regard for due process (正當程序).