Mobile users generate ever-increasing amounts of digital data, such as photos and videos, which they upload, while on the go, to online services. 3G connectivity enables mobile users to upload their data while on the go but drains the battery of their devices and overloads mobile service providers. Wi-Fi data offloading overcomes the aforementioned issues for delay-tolerant data. This, however, comes at the cost of constrained mobility for users as they are required to stay within a given area while the data is uploaded. The up-link of the broadband connection of the access point often constitutes a bottleneck and incurs waiting times of up to tens of minutes. In this paper, we advocate the exploitation of the storage capabilities of common devices located on the Wi-Fi access point LAN, typically residential gateways or set-top boxes, to decrease the waiting time. We propose Hoop, a system for offloading upload tasks onto such devices. Hoop operates seamlessly on HTTP(S) POSTs, making it highly generic and widely applicable; it also requires limited changes on the gateways and on the web server and none to existing protocols or browsers. Hoop is secure and, in a typical setting, reduces the waiting time by up to a factor of 46. We analyze the security of Hoop and evaluate its performance by correlating mobility traces of users with the position of the Wi-Fi access points of a leader ISP. We show that, in practice, Hoop drastically decreases the delay between the time the photo is taken and the time it is uploaded, compared to regular Wi-Fi data offloading. We demonstrate the practicality of Hoop by implementing it on a wireless router.