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.
Like a one armed hug, but only your arms are hugging while your head is nuzzling and you are giggling about whatever it is that makes you giggle :)
"Wanna go Pretzel?"
"urm, not really" ;)