Older male colleague flirting?

I can not decode the behaviour of one of my older colleagues at work (he is sort of my supervisor). During work hours, he is usually formal and correct, although he engages in extreme man-spreading (directed at me) almost every time we talk in his office, just the two of us. He teases me quite often and I have noticed him stealing glances of my body before, although I do not know if he just happened to look at that time, kind of like just resting his eyes, or if it was more intentional.

Sometimes we have afterwork activities for the office, and when we are out and have had a bit to drink he always start to touch my shoulders, standing kind of close, and playfighting with me (like teasingly bumping his body into mine). One time we were out at a bar with some colleagues, and started playing table tennis. He then smacked by bum with his racket.

I do not know how to react to his behaviour. Guys, is this flirting or is he just trying to be friendly?
Older male colleague flirting?
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