WATCH: SBW amazing after match act of kindness is what the world needs now!

Sonny Bill Williams really is one of rugby's good guys.

Two years after the New Zealand centre gave his World Cup final medal away to a young pitch invader at Twickenham, the 31-year-old has once again proved his generosity knows no bounds.

Williams was mingling with the Eden Park crowd following the All Blacks' impressive 30-15 win over the Lions.

The former rugby league player posed for a number of photos with visiting supporters before pausing to speak with a star-stuck young Lions fan.

With no medal to give away, the Auckland Blues centre instead took off his shorts and socks and handed them to the grateful young boy.

Williams gave his World Cup final medal to a young All Blacks fan back in October 2015 after the pitch invader was initially tackled to the ground by security.

"I was walking around doing a lap of honour with the boys and a young fella came running out and he got smoked by the security guard, like full-on tackled him. I felt sorry for the little fella.

"If that was a younger brother or cousin I would have given the security guard a hiding. But I just picked the kid up and took him back to his old lady and tried to make the night more memorable for him. Better [for the medal] to be hanging around his neck than mine."

- This article was first published on nzherald.co.nz and is republished here with permission.