Stray Kids' powerful 'Thunderous' took home its sixth comeback show win. Being proud of the immense achievements and growth of the boys is an understatement for STAYs.On September 9's M Countdown, Stray Kids' Thunderous went head-to-head with their senior BTOB's OUTSIDER. Both groups have brewed a special friendship, especially after their 'Mayfly' group performances. As Stray Kids took their sixth win on stage, BTOB also remained on stage and performed part of the encore together with their juniors.Stray Kids and BTOB perform 'Thunderous' on encore stageIn the latest episode of M Countdown, the first-place nominations were held by BTOB's OUTSIDER and Stray Kids' Thunderous. Fans experienced bittersweet emotions as both groups share a loveable friendship - a friendship where a few Stray Kids' members hang out at BTOB members' houses and occasionally eat with them.Stray Kids ended up bagging the trophy. Usually, only the group that wins No. 1 stays on stage and performs an encore of the song to thank fans. This time, however, BTOB stayed behind on stage, looking excited and praising their juniors for winning No. 1.BTOB's Minhyuk, Peniel and Eunkwang did the 'STAY signal', leading to leaders Bang Chan, Han, Changbin, Hyunjin and I.N doing the same. BTOB members even danced to the chorus of Thunderous, surprising everyone with their flawless moves.More than Stray Kids winning the trophy, fans are all over Twitter cherishing and loving the vivacious energy both the groups showed on stage.Check out some cute interactions from the encore stage below:Stray Kids Bangchan mentioned Btob in his winning speech"We received the trophy. But actually the fact that we stand together with Btob as nominees is a big honor for us. So I want to share this honor together with Btob"And that's how Btob joined their encore stage 😂😂😂 pic.twitter.com/a6dS3zGP2F— 💜🎶🌌💙 (@mel0dy1010_) September 9, 2021btob and skz doing the stay signal, i love them so much 😭🤍 pic.twitter.com/p83vfQQI8y— elise ⚡️ (@hwangsamericano) September 9, 2021for a group of btob's caliber & tenure to be so gracious, welcoming, & kindhearted to a relatively young group like skz.. a group they have even competed w & are "competing" w rn! so nice to see genuine friendship btween artists, esp this one that even spans (kpop) generations..— iona 🟤 (@i_on_a) September 9, 2021PLS BTOB AND SKZ INTERACTION IS EVERYTHING TO ME THIS IS SO CUTE pic.twitter.com/IbyzwMuuRK— 지노 (rest) (@skzinthedorm) September 9, 2021SKZ AND BTOB DOING THE STAY SIGNAL TOGETHER ON STAGE I CAN'T STAND THEM pic.twitter.com/rqvW65EZV4— 꿀 ✦⋆͛ (@seorecord) September 9, 2021this is now my new favorite skz x btob interaction T___T pic.twitter.com/3k4Pj56gs7— 화영 (@yslcheol) September 9, 2021btob + skz = chaos 😭 pic.twitter.com/2Pt0PAyNd1— ⚡ (@thrccracha) September 9, 2021On top of the lively and spirited stage they shared together, BTOB's Eunkwang unleashed his supportive big brother personality on Instagram. He shared a screenshot of them doing the STAY signal on stage, along with his selfies, on the platform. View this post on Instagram A post shared by 서은광 (@btob_silver_light)btob’s eunkwang posted this picture and his caption “feat mayfly sincerely congratulations” 🥺🤍 pic.twitter.com/gqDGCkTXc4— 댕꾸 ◡̈ (@SEUNGM1NE) September 9, 2021BTOB's Minhyuk became 'Fansite Minhyuk' and shared a video of Stray Kids in their waiting room last Sunday on Inkigayo. The Kids spotted Minhyuk and got all excited, jumping around and running toward the camera.BTOB Minhyuk called himself Fansite Lee Minhyuk 🥺😭 and the kids' excitement https://t.co/CIxvGd6k7o— n. (@skzvana) September 9, 2021Ever since they collaborated for performances on Mnet's Kingdom, Stray Kids and BTOB's interactions as the senior-junior group remain one of the cutest for fans.