Run this in the console of your github.com/<user> page (i.e. http://github.com/remy) and see how many weekends you were in front of a computer and committing code instead of taking a break.

weekend-commits.js

$.getJSON('https://github.com/users/' + location.pathname.replace(/\//g, '') + '/contributions_calendar_data', weekendWork);
function weekendWork(contribs) {
  var inwe = false, streak = 0, highest = 0, total = 0, possible = 0;
  contribs.forEach(function (c) {
    var d = new Date(c[0]).getDay();
    if (d === 6) {
      inwe = true;
    } else if (d === 0 && inwe) {
      possible++;
      if (c[1] !== 0) {
        total++; 
        streak++;
        if (streak > highest) highest = streak;
      } else {
        streak = 0;
      }
    } else {
      inwe = false;
    }
  });
  console.log('Potential weekends relaxing: ' + possible + ', total weekends working: ' + total + ', number of weekends IN A ROW working: ' + highest);
  if (highest > 0) console.log('Take a break. Have a kitkat');
}

I think @miguelff is right, there may be a bug in either the script, the data or the graph. The script says I worked 42 weekends but my graph doesn't look that bad:

I believe the inner if is inverted, line 10 should read if (c[1] !== 0) { instead. It does brings @remy's streak up by one :) Here're mine:

(orig) Potential weekends relaxing: 53, total weekends working: 14, number of weekends IN A ROW working: 10

(fixed) Potential weekends relaxing: 53, total weekends working: 14, number of weekends IN A ROW working: 3

Potential weekends relaxing: 53, total weekends working: 51, number of weekends IN A ROW working: 43
Take a break. Take a kitkat O_O

I'm sure there IS something wrong with the results, my graph is obviously much more scattered than this message:
Potential weekends relaxing: 53, total weekends working: 53, number of weekends IN A ROW working: 53
Take a break. Take a kitkat