The act of cuddling and other such public displays of affection (PDA) in an open area. Nesting is commonly done spontaneously with someone you don't particularly know very well.
Group nesting is called a Nest Fest.
This act can lead to Burrowing. Burrowing can lead to babies.

Nesting is a ritual performed by pregnant women in ridding the house, the "nest", from anything potentially harmful to the soon to be born child.
This can also be seen as a phase before menstruation where the woman enjoys cuddling and snuggling more than usual.

In the culture and lifestyle of apartment life, nesting is the act of settling yourself into a cozy convenient corner of your bedroom and surrounding yourself with all the comforts of your many vices.
i.e. a bed pushed against a wall with a window for smoking, internet access, porn, toilet paper, beer fridge, TV/DVD, game console, beer fridge, hash pipe, etc.

The act of covering a toilet seat in toilet paper to avoid contamination from urine and tiny shit particles on the seat.

The act of draping sheets of toilet paper between the toilet seat and toilet bowl until one has created a net in which to catch one's poop so that no defecation sound ("poop plunk") is audible to potential boyfriends sitting in the other room.

The process of resting post squirrelling, gaining the strength to carry on.

To go to the nest. To retreat to the place hawks live, the nest. To stay with other hawks at the nest;