In endurance sports, particularly cycling and running, hitting the wall or the bonk describes a condition caused by the depletion of glycogen stores in the liver and muscles, which manifests itself by precipitous fatigue and loss of energy. Milder instances can be remedied by brief rest and the ingestion of food or drinks containing carbohydrates. The condition can usually be avoided by ensuring that glycogen levels are high when the exercise begins, maintaining glycogen levels during exercise by eating or drinking carbohydrate-rich substances, or by reducing exercise intensity.
I bonked at 80 miles, just nothing left in the legs.

I completed the marathon without bonking.
by BodyAttacker April 25, 2011
Communicating via various online chat platforms while sober yet implementing an inebriated persona due to an overall lackadaisical disposition.
He was IMing me all night, bonking as he always does.
by Alley Cats October 26, 2011
The word BONK is used in conversation to alert the other party that you are horny. It is often followed by the expression "go to horny jail" if it does not result in a sexual act taking place.

BONK, is derived from a meme which circulated during the 2020 coronavirus outbreak. The meme depicts a dog hitting another dog on the head with a baseball bat with the text "BONK", "go to horny jail.
Her: "Ah my boobs are achy today"
Him: "BONK"
Her: "Go to horny jail"
by hglly April 26, 2020
Having sex. It's a word that is widely acceptable in British society - not as rude as shag and *far* less rude than the offensive fuck.
The London Times recently wrote that President Bill Clinton "may forever be known as Bonking Bill."
by martin November 13, 2003
a 'bonk-on' is another term used to describe an erect penis due to arousal
"my God Dave, did you see that girl?! she's fine! I've got a bit of a bonk-on now"
by TomTom20 June 23, 2008
Expression used by cyclists to describe excercise induced low blood sugar levels; being a feeling of light-headedness and weakness in all limbs. Similar to 'The Wall' in running. Has fallen out of usage in recent years due to alternative meanings.
I am feeling a bit light-headed, if I don't have a banana, I think I'm going to bonk.
I've got the bonk.
I bonked really badly and had to get a lift home.
by Comedy Dave June 5, 2004