MacDonald, Macdonald, and McDonald are anglicized forms of the Scottish/Irish Gaelic name "Mac Dhomhnuill", a patronymic from the personal name "Domhnall". Domhnall means world ruler and Mac means son of.
In the context of Scottish Clans, the various forms of the name refer to one of the largest clans, Clan Donald.
A fast food place that wants to dominate the world's eating habits, found in virtually every inhabited country and without doubt the worst food provider ever. MacDonald's food makes you puke and is quite disgusting in general. Big Mac is the main product, lots of burgers too with plastic cheese on them (the cheese is partly taken from cowgut). Eat it at your own risk. Morgan Spurlock made a film called Supersize Me, in which he ate nothing but MacDonald's food for 1 month and at the end of it was in a very poor state of health, it took him several months to recover.
Person A: I found a MacDonald's!
Person B: But is there anywhere we can eat without being sick?