Slipping

There are many definitions for the word slip. Here are a few of the most common expressions for the verb from.

#1) My English skills are slipping. = My English skills are getting worse.

Sample Situation: You used to be proud of your English skills, but now you find it hard to communicate.

#2) It slipped my mind. = I knew about it, but I forgot (temporarily).

Sample Situation: You had an appointment with your friends, but you completely forgot about it and didn't go.

#3) I slipped up. = I made a mistake.

Sample Situation: You were at a party and you tried to kiss your girlfriend's sister.

#4) It just slipped out. = I said it on accident.

Sample Situation: When you argued with your girlfriend, you told your girlfriend to shut up, perhaps adding a swear word or two. You quickly regret saying it.