user12009: The following dialogue is between two chess players at the end of a game. Does it mean "you have lost 4 games so far, what is your idea about going for the 5th game and developing the competition to 8 games"?
Dialogue:

A: Checkmate! Care to try for best five out of eight?
B: No, Thank you.

The source: http://www.clockwork-comics.com/2012/09/06/i-like-the-way-you-think-schlumberger/

user12014: Essentially, you would not ask for "best five out of eight" unless you have, excluding draws,

lost 4 points
can win 5 points within 8 games.

But these together are mathematically impossible, as that would require 9 games.
It doesn't get better if draws are allowed.
The reply should be "best 5 out of 9."

user7297: To me, it just seems A is asking for a match of 8 games. If you exclude the possibility of draws, you'll need 5 wins to win such a match. This is similar to the best-of-X formats used in playoffs in many sports.
In any case, it's not terminology specific to chess. You might have more luck on English Language & Usage or English Language Learners.

12009: <p>The following dialogue is between two chess players at the end of a game. Does it mean &quot;you have lost 4 games so far, what is your idea about going for the 5th game and developing the competition to 8 games&quot;?</p>
<p>Dialogue:</p>
<blockquote>
<p>A: Checkmate! Care to try for best five out of eight?</p>
<p>B: No, Thank you.</p>
</blockquote>
<p>The source: <a href="http://www.clockwork-comics.com/2012/09/06/i-like-the-way-you-think-schlumberger/" rel="nofollow noreferrer">http://www.clockwork-comics.com/2012/09/06/i-like-the-way-you-think-schlumberger/</a></p>
 12014: <p>Essentially, you would not ask for "best five out of eight" unless you have, excluding draws,</p>

<ol>
<li>lost 4 points</li>
<li>can win 5 points within 8 games.</li>
</ol>

<p>But these together are mathematically impossible, as that would require 9 games.</p>

<p>It doesn't get better if draws are allowed.</p>

<p>The reply should be "best 5 out of 9."</p>
 7297: <p>To me, it just seems A is asking for a match of 8 games. If you exclude the possibility of draws, you'll need 5 wins to win such a match. This is similar to the <a href="https://en.wikipedia.org/wiki/Playoff_format#Best-of_formats" rel="nofollow noreferrer">best-of-X</a> formats used in playoffs in many sports.</p>

<p>In any case, it's not terminology specific to chess. You might have more luck on <a href="https://english.stackexchange.com/">English Language &amp; Usage</a> or <a href="https://ell.stackexchange.com/">English Language Learners</a>.</p>
