Spirit level 

Woman on all fours with cum coming out equally from her arse and both sides of her mouth

When a woman is on all fours with cum coming out equally from her arse and both sides of her mouth, the floor is level - she is a "spirit level".

Spirit level by The Builder 71 February 15, 2009

learning curve like a spirit level 

Description of someone extremely slow to pick things up.

Jim's been losing at three-card monty for 3 hours now - damn he's got a learning curve like a spirit level!

learning curve like a spirit level by Iain1977 February 21, 2008

the human spirit level

whilst one is renovating a house and needs to determine the level of the newly constructed floor, he requests that a girl sits on the floor on all fours. He then proceeds to blow in each end and observe which end it drips out of giving him clear indication of which end of the floor is out of level.

Carly can you come around to my house im renovating and need the human spirit level.

the human spirit level by the two bob lobber July 31, 2012

Spirit leveling 

When you fart and a bubble feels like it moving up and down your are crack

I just farted and now it's spirit leveling

Spirit leveling by Stan Stanley stanforth May 3, 2019