No matter how much you  push the envelope, it’ll still be stationery.
“To push the envelope” is an expression that means to exceed or try to exceed the normal limits. “Stationery” is writing materials such as paper and envelopes.  “Stationary” (-ary) means to not move.  This pun plays with the word stationery/ stationery and the idea of pushing something (moving something) and staying still (stationary).

Whoever invented knock-knock jokes should get a no-bell prize.
If you knock on the door you do not use the doorbell.  “No-bell prize” sounds like Nobel, Nobel Prize.  This pun plays with the words no-bell/ Noble.

Energizer Bunny Arrested: Charged with Battery

• When people are arrested they are charged with a crime.
• One of the crimes you can be charged with is battery (verb): contact that hurts another person.
• A battery (noun) is a small energy source that might be put in a flashlight or radio.
• The Energizer Bunny is a toy that is used by Energizer Batteries to advertise their products.  The Energizer Bunny toy uses batteries, that is, it gets its power from batteries: it is charged with batteries.

This pun plays with the words battery and charged and their double meanings.

I put my grandma on speed dial.  I call that Instagram.
Speed dial is one button on a phone that dials instantly someone’s telephone number.  If a speed dial button is programmed to call grandma then it dials grandma instantly.  Combine instantly and grandma and you get insta-gram  which sounds like Instagram, a photo sharing website… you also get a punderful pun!