Putting aside why you would want to do it, I would say it is not safe to use a pencil in that way. There is obviously a sharp end which could easily penetrate the membrane of the rectum, but I would also think the diameter of the unsharpened end could cause similar damage.
This could lead to a number of conditions such as localised trauma causing bleeding and pain, or more seriously cause a severe infection like peritonitis or septicaemia, which can easily result in death, or a long stay on the ICU attached to a ventilator at least. You may also require abdominal surgery and end up with a colostomy, where the bowel is redirected from the rectum to the side of the abdomen. This would require a bag sticking over the opening or 'stoma' to collect the faeces. Also, if your bowel became swollen, the surgeons may need to leave your abdomen cut open with a transparent dressing in place for a number of weeks until it heals and they are able to close the wound.
As a medical practitioner I would strongly advise you do not insert sharp objects with the diameter and rigidity of a pencil into your 'bum' as it could, at the very worst, cause death. If you do gain pleasure from anal stimulation either buy a device made for the job or use something which could not cause trauma. A good rule of thumb would be not to put anything up there if it could easily pop a half inflated balloon.
If you are going to do it anyway, which I reiterate I do not advise, simply coat the implement with a suitable lubricant and slowly slide it into you anus. Bear in mind that the anus and rectum have a specific use biologically and you may come into contact with unpleasant bodily waste.
put the pencil into a measuring jug filled with water to 100g the when you put the pencil in you see how much it has gone up . if it has gone up to 150g the pencil will the 50g in area. because you put in 100g of water
you put it up your bum... 'nuff said
up ur bum
They don't.
put it up your bum
They put it up their bum
# at you bum bum bum bum bum bum bum bum # up you # i love you # hhhhhhhhhhhhhhhhheeeeeeeeeeeeeeeeeeeellllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllloooooooooooooooooooooooooooo# at you bum bum bum bum bum bum bum bum # up you # i love you # hhhhhhhhhhhhhhhhheeeeeeeeeeeeeeeeeeeellllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllloooooooooooooooooooooooooooo
up the bum
put it up your bum
hello everybody everybody is a bum and shut up
get your mams bum hole and put a apple up it then lick her teeth.
no it is tactically sperm cells :s