What does くり mean?

Question

What does くり mean after the stem of ます form?

いやいやいや、わかりまくりでしょ。優ちゃんが読んでるその本にも書いてあるしさ。

Answer 1

The word is 「まくり」 and not 「くり」.

「Verb in 連用形{れんようけい} "continuative form" + まくる」

means:

"to do a lot of", "to (verb) like crazy", "to (verb) very easily and/or completely", etc.

「まくり」 is the noun form of the verb 「まくる」.

Thus, 「わかりまくりでしょ」 means "You get/understand it completely, dontcha?"

"Nah, nah, nah, you get it completely, dontcha? (Coz) It's discussed in the book you're reading, too."

(I am assuming that 優ちゃん is the name of the listener.)