An example of a triplet groove in 4/4 that came to mind is 'Can't Help Falling in Love with You' by Elvis Presley - https://youtu.be/vGJTaP6anOU?si=2d_OalSqAn-CBmjd - this one you can count triplets in 4 (1+a 2+a 3+a 4+a).
If anyone in here has some other examples post them in the comments below!