Learn English – the meaning of ‘Past the point’

It's a modification of the word ridiculous, using donk /dɑŋk/ to replace dic /dɪk/:

Absolutely ridiculous!

As you might expect, redonkulous sounds a bit silly. It's considered slang, and only certain people use the altered word. Although it means "ridiculous", it's non-standard and markedly informal.

I haven't seen the movie in question, but it looks like the bird is repeatedly using the word. My guess is that it's because rendonkulous sounds silly and is supposed to make the audience laugh.

I've never heard this before, either, but it reminds me of the idiomatic expression six ways to Sunday, which, according to Wiktionary, means:

in every way imaginable

When discussing this phrase, WiseGEEK mentions:

Before becoming the title of a late 1990s mob-related movie staring Deborah Harry, the idiom "six ways to Sunday" was a less commonly used English expression meaning every way possible, thoroughly, or completely. Tracing the roots of such idioms is not always easy, [but] the meaning behind six ways to (or from) Sunday can be deciphered based on logical assumptions.

In terms of the calendar, there are six days after Sunday, or six days before Sunday, depending on the perspective. The phrase points out the inevitability of reaching Sunday, no matter what day serves as starting point.

Given that, I'd interpret the remark to mean:

You're dead – in every way imaginable!

meaning that death will inevitable for that character (unless something is done about the situation).