Since it was summer in Korea, a female fan wore a summer (sleeveless) dress. But sadly, the venue had an aircon inside so it was cold. 
When she went up the stage for autographs, the EXO members noticed she was feeling cold, since she wasn't wearing any jacket and the room was kinda cold. 
The members felt 'worried' and kept asking her if she was feeling okay. The fangirl just smiles and nods. But when she went to Lay...

Lay: Are you okay?
Fan: Yes~ *smiles*
Lay: Do you feel cold?
Fan: *smiles* I'm okay~ 
Lay: Do you need my jacket? *stands up and was about to take off his jacket*
Fan: *stops him; shakes head* No, no~ I'm really okay!~

Then another fan, who was beside the fangirl and who may have overheard the fangirl and Lay's conversation, said:
"She's okay! I'll lend her my extra jacket!"

credit: мιƨƨαℓɛιиα