There is a widespread belief that Roundup® (active ingredient: glyphosate) is safe enough to drink. Indeed, my neighbor informs me of this every time he sees me pulling weeds in my garden.
The majority of GMOs are genetically modified to withstand direct application of herbicides. One of the most common is marketed as Roundup Ready®, engineered to withstand glyphosate. The result is that glyphosate residues are in our food. Just last summer the EPA raised the allowable levels of glyphosate in our food, in spite of receiving over 10,800 public comments against the proposed change. Whether or not it's safe enough to drink, we are certainly eating it.
Based on this 1947 video, drinking and eating pesticides seems to be one of Monsanto's favorite marketing tools. In the video, an entomologist is sent to an African village to try to convince them to spray DDT all over the village to kill the mosquitoes. But the Africans aren't buying it. The entomologist calls for a bowl of porridge, proceeds to spray DDT all over it and then eats a few bites. The Africans are still not buying it.