(For s.t. or s.o. different) to come into a group; to include s.t. different; (for s.t. or s.o. different) to slip s.t. into (a group/conversation).
The -an suffix is used when focusing more on the thing that is being participated in or the thing one is including s.t. in. The pa-un imp. is focusing more on what is being included into/in s.t.
Children today no matter how well they speak Mapun, for sure they will have some English slip into their speaking.
When you speak, don't always just use Mapun, but rather slip in your English once in awhile also.