pile on

Short definition from Wiktionary

Verb

1. 1
   To jump on top of someone or something quickly.
2. 2
   To criticize someone or something in a concerted effort; to add on some additional critique.
3. 3
   To unnecessarily extend the margin of a winning score.
4. 4
   To add or apply in great quantities.

Noun

1. 1
   Nonstandard spelling of pile-on.
2. 2
   An argument or fight in which one side is greatly advantaged by being more numerous or more closely allied than the other side.