Like Spooning only more so. Maximum body to body contact. Some people do not like this, because they lose circulation and have various body parts go numb, but a small, dedicated, sensual sub-section of people are naturally drawn to this hyper-contact activity. Can occur before, or after, or independent of sex.

When you and your partner (male or female) cross your legs behind your head and engage in sex

When someone eats everything but the pretzels in a snack mix.

Pretzellation is when a group of arse-licking people are friends with each other and are so far up each others arses they are entangled in a pretzel formation

v. Intertwining oneself with another while laying down, preferably with someone of the opposite sex. Can be done with or without intercourse.

A way of saying that someone looks stoned in the midlands.

A recent study found that 7/10 potheads in Herefordshire used this while telling a friend they looked fucked in the venue.

The act of sitting close to a person, side-by-side, but facing opposite directions, and interlocking one arm each to form a pretzel.
This could be considered a prequel to cuddling, since resting your head on their shoulder, nuzzling, and tracing your fingers over their arm, etc. is acceptable, and expected.
On the base system it would be before first base; and on the snogging scale it would be an approximate 2.5.