This is the special ability unlocked when you reach a 75% or more 'like' with Little Jacob. To check how much percent Little Jacob Likes you, you can find it under 'General' in the Stats section.
To increase the like percentage of a character you will need to hang out with them. But be careful not to wake them up or phone them too often as the like percentage will decrease.
Little Jacob is awake from 1pm to 4am.
He likes Darts, drinking, eating, pool, watching shows and going to strip clubs.
Some credit goes to 'Khaos' from xbox360acheivemnts.org for the activity information about Little Jacob.