please tell me

Helvetica Bold  Suggested by Heron2001 

but what about the pattern in it

I'm sorry - I thought it was a bad reproduction - old type on old wrinkly paper.
There may be a font like this - but it is easy to create similar in Photoshop.

I would look here: http://www.dafont.com/theme.php?cat=107&text=STOP+QUICKLY!&fpp=100

Thanks