Welp, sup, yep, yup, nope
Though we have presented quite a bit of informal and recent use, our earliest written use of welp goes back over 70 years. It shows up in a scholarly article on two of welp’s linguistic cousins: yep and nope. Well gained that final -p as part of a normal process of articular: the lips come together to stop the sound of well and prepare for the next sound, and some hear that stoppage as a -p. This means it is very common in speech. One linguist went so far as to say that anyone who didn’t know what welp meant was probably an alien.